]>
Linux Complete Backup and Recovery HOWTO 2002 January 20 Charles Curley
&myemail;
2.3 2007-05-26 c^2 Changes for FHS compliance. Changes in save.metadata to handle the libata problem. 2.2 2006-07-11 c^2 Clarified that the ZIP disk is not required, and there are alternatives. 2.1 2006-03-28 c^2 Added notes for NTFS. Edited the To Do list. Started work on LVM and using Finnix. 2.0 2005-10-12 c^2 Notes for Fedora Core 4. Removed notes for older versions of FC and Red Hat. Also, changes in the writeup and scripts to reflect using Knoppix instead of tomsrtbt. See the scripts for change notes. Changed some scripts so that long lines don't fall off the right side of printed pages (oops). 1.8 2005-02-19 c^2 Added notes for Fedora Core 3 1.7 2004-05-11 c^2 Adjusted copyright language. 1.6 2004-04-29 c^2 Added Knoppix notes, Syslinux, PPART, QtParted, some other rescue CDs, and made some fixes. 1.5 2003-12-19 c^2 Fedora 1 and GRUB notes. 1.4 2003-08-17 c^2 Some notes on burning CD-ROMs, and more on files to exclude. 1.3 2003-04-24 c^2 Substituted new email address and URL for old. 1.2 2003-02-12 c^2 Added Red Hat 8.0 notes, support for FAT32, split the first stage restore scripts, and other minor changes. Notes on Amanda. 1.1 2002-09-10 c^2 New code to handle ext3 partitions in make.fdisk, and a note on initrd. 1.0 2002-07-24 c^2 We now use bz2 compression in the first stage, have the run time option to check for bad blocks, and have a script that runs the entire first stage. Imagine your disk drive has just become a very expensive hockey puck. Imagine you have had a fire, and your computer case now looks like something Salvador Dalĩ would like to paint. Now what? Total restore, sometimes called bare metal recovery, is the process of rebuilding a computer after a catastrophic failure. In order to make a total restoration, you must have complete backups, not only of your file system, but of partition information and other data. This HOWTO is a step-by-step tutorial on how to back up a Linux computer so as to be able to make a bare metal recovery, and how to make that bare metal recovery. It includes some related scripts. Introduction The normal bare metal restoration process is: install the operating system from the product disks. Install the backup software, so you can restore your data. Restore your data. Then you get to restore functionality by verifying your configuration files, permissions, etc. The process and scripts explained in this HOWTO will save re-installing the operating system. The process explained here will restore only files that were backed up from the production computer. Your configuration will be intact when you restore the system, which should save you hours of verifying configurations and data. Copyright Information Copyright © 2001 through last date of modification Charles Curley and distributed under the terms of the GNU Free Documentation License (GFDL) license, stated below. Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1.1 or any later version published by the Free Software Foundation; with no Invariant Sections, with no Front-Cover Texts, and with no Back-Cover Texts. A copy of the license is included in the section entitled GNU Free Documentation License. If you have any questions, please contact linux-howto at metalab.unc.edu. Disclaimers No liability for the contents of this documents can be accepted by the author, the Linux Documentation Project or anyone else. Use the concepts, examples and other content at your own risk. There may be errors and inaccuracies that may damage your system. Proceed with caution, and, although errors are unlikely, the author take no responsibility for them. All copyrights are held by their by their respective owners, unless specifically noted otherwise. Use of a term in this document should not be regarded as affecting the validity of any trademark or service mark. Naming of particular products or brands should not be seen as endorsements. You are strongly recommended to take a backup of your system before major installation and backups at regular intervals. In addition, you are strongly recommended to use a sacrificial experimental computer when mucking with the material, especially the scripts, in this HOWTO. New Versions You can find this document at its home page or at the Linux Documentation Project web site in many formats. Please comment to &myemail; Depending on your browser, you may have to hold down the shift button while you click on these in order to get them to download. bzip2 compressed chunky (lots of small pages. Faster reading.) HTML. bzip2 compressed smooth (one monster page -- no chunks. Easier to search.) HTML. bzip2 compressed postscript (US letter format). bzip2 compressed PDF (US letter format). bzip2 compressed raw ASCII text. Use the source, Luke. MD5 and SHA1 sums. To ensure that you got a good download, validate the files against the checksums above. The easiest way to do this is to pull in the sha1sum or md5sum files (or both), and run the appropriate program against it: $ sha1sum -c sha1sums or/and $ md5sum -c md5sums Credits This document is derived from two articles originally published in Linux Journal. My thanks to Linux Journal for reverting the rights to those articles, thereby helping make this HOWTO possible. Thanks to Joy Y. Goodreau for excellent HOWTO editing, and to David Palomares for correcting the spelling of Salvador Dalĩ's name. Also, thanks to Pasi Oja-Nisula for a bug fix and information on Knoppix. Feedback Feedback is most certainly welcome for this document. Without your corrections, suggestions and other input, this document wouldn't exist. Please send your additions, comments and criticisms to me at: &myemail;. Translations Not everyone speaks English. Volunteers are welcome. Overview The process shown below is not easy, and can be hazardous to your data. Practice it before you need it! Do as I did, and practice on a sacrificial computer! The original target computer for this HOWTO was a Pentium computer. Originally, it had a Red Hat 7.1 Linux server or workstation installation on one IDE hard drive. Since then, I have used a number of computers, and they have been ugraded to Red Hat 8.0 and Fedora Cores 1, 3 and 4.. The target computer does not have vast amounts of data because the computer was set up as a sacrificial test bed. That is, I did not want to test this process with a production computer and production data. Also, I did a fresh installation before I started the testing so that I could always re-install if I needed to revert to a known configuration. NOTEThe sample commands will show, in most cases, what I had to type to recover the target system. You may have to use similar commands, but with different parameters. It is up to you to be sure you duplicate your setup, and not the test computer's setup. The basic procedure is set out in W. Curtis Preston, Unix Backup & Recovery, O'Reilly & Associates, 1999, which I have favorably reviewed in Linux Journal. However, the book is a bit thin on specific, real-time questions. For example, exactly which files do you back up? What metadata should you preserve, and how? This document explores those questions. Before beginning the process set forth in this HOWTO you will need to back up your system with a typical backup tool such as Amanda, BRU, tar, Arkeia or cpio. The question, then, is how to get from toasted hardware to the point where you can run the restoration tool that will restore your data. Users of Red Hat Package Manager (RPM) based Linux distributions should also save RPM metadata as part of their normal backups. The following is in one of the scripts in this HOWTO: bash# rpm -Va | sort +2 -t ' ' | uniq > /etc/rpmVa.txt It provides a basis for comparison after a bare metal restoration. To get to this point, you must have: Your hardware up and running again, with replacement components as needed. The BIOS should be correctly configured, including time and date, and hard drive parameters. At the moment, there is no provision for using a different hard drive. When I started this project, I used a ZIP drive. Now, they are rather cramped for space and can be inconvenient. You can substitute a USB flash disk, NFS mount, CD-RW or other medium. Just be sure that the Linux distribution you use for first stage restore supports your medium. For historical reasons, this document will refer to the ZIP drive; please substitute the medium of your choice. There is more discussion of alternatives below in the section on Theme And Variations. Your normal backup media: tape hard drive, etc. A minimal Linux system that will allow you to run the restoration software, which we will call the restoration Linux. To get there, you need at least two stages of backup, and possibly three. Exactly what you back up and in which stage you back it up is determined by your restoration process. For example, if you are restoring a tape server, you may not need networking during the restoration process. So only back up networking in your regular backups. You will restore in stages as well. In stage one, we build partitions, file systems, etc. and restore a minimum of files from the ZIP disk. The goal of stage one is to be able to boot to a running computer with a network connection, tape drives, restoration software, or whatever we need for stage two. The second stage, if it is necessary, consists of restoring backup software and any relevant databases. For example, suppose you use Arkeia and you are building a bare metal recovery ZIP disk for your backup server. Arkeia keeps a huge database on the server's hard drives. You can recover the database from the tapes, if you want. Instead, why not tar and gzip the whole arkeia directory (at /usr/knox), and save that to another computer over NFS or SSH? Stage one, as we have defined it below, does not include X, so you will have some experimenting to do if you wish to back up X as well as your backup program. Some restore programs require X. Of course, if you are using some other backup program, you may have some detective work to do to. You will have to find out the directories and files it needs to run. If you use tar, gzip, cpio, mt or dd for your backup and recovery tools, they will be saved to and restored from our ZIP disk as part of the stage one process describe below. The last stage is a total restoration from tape or other media. After you have done that last stage, you should be able to boot to a fully restored and operational system. Limitations This HOWTO is restricted to making a minimal backup such that, having then restored that backup to new hardware (bare metal), you can then use your regular backups to restore a completely working system. This HOWTO does not deal with your regular backups at all. Even within that narrow brief, this HOWTO is not exhaustive. You still have some research, script editing, and testing to do. The scripts here restore the partition data exactly as found on the source hard drive. This is nice if you are restoring on an identical computer or at least an identical hard drive, but that is often not the case. For now, there are two remedies (which will make more sense after you've read the rest of the HOWTO): Edit the partition table input file. I've done that a few times. You can also do this to add new partitions or delete existing ones (but edit the scripts that use the partition table input file as well). Hand build a new partition table and go from there. That is one reason why restore.metadata does not call the hard drive rebuilding script. Use the rebuilding script. The scripts shown here only handle ext2fs, FAT12, FAT16 and FAT32. Until some eager volunteer supplies code for doing so in these scripts, you will need other tools for backing up and restoring file systems we haven't covered. However, see the note below on NTFS. Partition Image looks like a useful candidate here. Preparation WARNING Do your normal backups on their regular schedule. This HOWTO is useless if you don't do that. Build yourself a restoration Linux disk. I have used Knoppix. See the notes on Knoppix below. However, everything here is command line. We don't need a GUI. A GUI-less distribution will boot faster and can load itself into memory (so you can use the CD drive) even on a minimal machine. For this I now use Finnix. In the past, I have used tomsrtbt. It is well documented and packs a lot of useful tools onto one floppy diskette. Unfortunately, the changes I've had to make in the scripts to handle more recent Linux systems cause problems for tomsrtbt. The tomsrtbt 2.0.103 tar is based on busybox, so remarks about it may apply to other Linux disties which use busybox. Next, figure out how to do the operating system backup you will need so that you can restore your normal backup. I used to follow Preston's advice and use an Iomega parallel port ZIP drive. The drives get approximately 90 MB of useful storage to a disk. I need about 85 MB to back up my desktop, so a 100MB ZIP drive may be pushing your luck. These days I use CD-RWs or NFS. For more on those, see the sections on using CD-ROMs and NFS. Installing the ZIP Drive Installing the ZIP drive is covered in the ZIP Drive HOWTO, available at the Linux Documentation Project and at its home page, http://www.njtcom.com/dansie/zip-drive.html. Backup Server You can set up a backup server for this process. Scripts on the backup server interact with the target machines (including itself) via SSH. They assume that your backup server user (root here, for simplicity) can log in with no password to the targets. This is necessary for unattended backups. First, create a suitable directory to keep all the backups in. We'll call it backs. In backs, create a directory for each target computer. The first field in the directory should be the host name. Subsequent fields can be other useful information. For example, to preserve the last backup of a target before an installation of a new version of the distribution, I use an abbreviation for the distribution, e.g. fc5. Fields are separated with periods (.). So, for example, tester.f7. The host name is required because the scripts use that to determine which host to back up. Copy the scripts get and restore into each target's directory. Then customize them for each host as needed. Also create in backs a directory called scripts and put in it the script get.target. This is a library for the backup and restore scripts. It performs actions common to all backups and restorations. Creating the Stage 1 Back Up Having made your production backups, you need to preserve your partition information so that you can rebuild your partitions. The script make.fdisk scans a hard drive for partition information, and saves it in four files. The first is an executable script, called make.dev.x (where x is the name of the device file, e.g. hda). Second is mount.dev.x, which creates mount points and mounts the newly created partitions on them. The next, dev.x, is the commands necessary for fdisk to build the partitions. Last is an input file for sfdisk to create partions. (sfdisk is preferable and used if found.) You specify which hard drive you want to build scripts for (and thus the file names) by naming the associated device file as the argument to make.fdisk. For example, on a typical IDE system, bash# make.fdisk /dev/hda spits out the scripts make.dev.hda, mount.dev.hda and the input files for fdisk and sfdisk, dev.hda and dev.hda.sfd, respectively. In addition, if make.fdisk encounters a FAT partition, it preserves the partition's boot sector in a file named dev.xy, where x is the drive's device name (e.g. sdc, hda) and y is the partition number. The boot sector is the first sector, 512 bytes, of the partition. This sector is restored at the same time the partitions are rebuilt, in the script make.dev.hda. Fortunately, the price of hard drives is plummeting almost as fast as the public's trust in politicians after an election. So it is good that the output files are text, and allow hand editing. That's the most difficult but most flexible way to rebuild on a larger replacement drive. (See the To Do list.) Other metadata are preserved by the script save.metadata. The script saves the partition information in the file fdisk.hda in the root of the ZIP disk. It is a good idea to print this file and your /etc/fstab so that you have hard copy should you ever have to restore the partition data manually. You can save a tree by toggling between two virtual consoles, running fdisk in one and catting /etc/fstab or /fdisk.hda as needed. However, doing so is error prone. You will also want to preserve files relevant to your restoration method. For example, if you use NFS to save your data, you will need to preserve hosts.allow, hosts.deny, exports, etc. Also, if you are using any network-backed restoration process, such as Amanda or Quick Restore, you will need to preserve networking files like HOSTNAME, hosts, etc. and the relevant software tree. The simplest way to handle these and similar questions is to preserve the entire /etc directory. There is no way a 100 MB ZIP drive is going to hold a server installation of a modern distribution of Linux. We have to be much more selective than simply preserving the whole kazoo. What files do we need? The boot directory. The /etc directory and subdirectories. Directories needed at boot time. Device files in /dev. To determine the directories needed at boot, we look at the boot initialization file /etc/rc.sysinit. It sets its own path like so: Trial and error indicated that we needed some other directories as well, such as /dev. In Linux, you can't do much without device files. In reading the script save.metadata, note that we aren't necessarily saving files that are called with absolute paths. We may require several iterations of back up, test the bare metal restore, re-install from CD and try again, before we have a working backup script. While I worked on this HOWTO, I made five such iterations before I had a successful restoration. That is one reason why it is essential to use scripts whenever possible. Test thoroughly! One thing you can do on an RPM based system is use the rpm program to determine which files are where. For example, to get a complete list of the files used by the openssh package, run: bash# rpm -ql openssh There are some things you don't need, like the man pages. You can inspect each one and decide whether to back it up or not. WARNING The second stage of restoration is run without overwriting previously restored files. This means that the files restored in the first stage are the ones that will be used after full restoration. So update your bare metal backups whenever you update files in these directories! WARNING Recent kernels have incorporated a new ATA (IDE) hard drive driver, libata. Because of this, parallel ATA drives (PATA) now show up as SCSI drives, as serial ATA (SATA) have always done. However, not all rescue distributions (e.g. finix) use this new driver. There is a line toward the bottom of save.metadata wich very carefully replaces "/dev/sda" with "/dev/hda". Use this as a template if you have multiple IDE hard drives. Comment it out or delete it if this is not an issue for you. Note that there is no guaranteed mapping! Systems with multiple hard drives may have confusing mappings. Be sure to edit this line carefully. Check it if you add or remove a hard drive of any interface type to or from your system! N.B: if you have libata IDE drive issues, the grub-install line at the end of restore.metadata won't work. If it doesn't, use your rescue disk to do the same. Or burn and boot to the boot image that is made as part of the first stage backup. Boot to it and do the second state restore as usual. The second state restore should re-run grub-install or you can run it manually. WARNING The version of tar included in tomsrtbt does not preserve ownership when it restores. This may cause problems for applications like Amanda. A backup and restoration tool, Amanda has several directories owned by its own eponymous user. The solution is: Note which directories and files are not owned by root. Note their owners. Arrange to set the ownership correctly as part of the restoration process. E.g: bash# chown -R amanda:disk /var/lib/amanda You can also add that line to your scripts for second state restoration, such as restore. WARNING tomsrtbt does not support restoring owners by UID/GID. To make backups suitable for restoring with tomsrtbt, remove the tar command line option --numeric-owner from the command line options for tar in the function crunch in the script save.metadata. The Archive All of this gets stored into an archive under /var/lib/bare.metal.recovery. Each day a first stage backup is made a new directory is prepared, with the date encoded as YYYYMMDD, and the day's archive deposited therein. It is up to you to prune obsolete archives. It is a good idea to keep at least one old archive around in case the computer crashes while you are making an archive. If a second archive is made in a day, the earlier one for that day is replaced. The files in the archive directory include a README.txt, which has information about the backup and the computer the backup was made on. Other files are there in case hand intervention is required. Below the daily archive directory are several text files and three directories. The scripts reside in bin, the tarballs in data, and information about the system such as partitions and LVM volume backups are in metadata. To create a CD, simply use a script or graphical tool to create a CD starting at the daily archive directory. It is up to you to be sure your archive will fit onto your medium, or to make other arrangements. Theme And Variations No ZIP drive This backup process used to require you to have the ZIP disk drive present at each backup. It now creates the archive in a directory, which you can back up over the net. Then you only need to build a ZIP disk (with cp -rp) on the backup server when you need to restore. The backup process will be faster than directly writing to the ZIP drive, but you should check that the resulting directory will fit on your ZIP disk (with the output of du -hs $target.zip in the script save.metadata)! See the definition of the variable zip in that script. One of my laptops has problems running both a network card and a ZIP drive, so this is the process I use to back it up. I keep a backup image as well as the current one, so that I have a fallback in case the computer crashes during a backup. CD-ROM This is similar to the no ZIP drive option above. Save your backups to a directory on your hard drive, as noted. Then use mkisofs to create an ISO 9660 image from that directory, and burn it. This does not work with some CD-ROM based restoration Linuxes, like Knoppix, because the Linux has to have the CD-ROM drive. Unless you have two CD-ROM drives, say one in a USB clamshell. I have a DVD burner set up this way with exactly this in mind. Or have Finnix load itself into memory on boot and then use the CD-ROM drive from which you booted. These remarks should also apply to DVDs. Also, look at remastering Knoppix with your first and second stage backups on the CD-ROM. You should also be able to remaster Finnix. These days many computers come with a CD-ROM drive but no floppy diskette. And floppy drives do fail. So it's a good idea to burn your CD-ROM with a bootable image on it. The bad news is that the El Torito format supports 1.2 MB, 1.44 MB and 2.88 MB floppy images, and tomsrtbt uses a 1.7 MB floppy. The good news is that you can get a 2.88 MB version, tomsrtbt-2.0.103.ElTorito.288.img, from the same mirrors where you get the floppy image. Place a copy I emphasize copy because mkisofs will mung the file in the directory from which it makes the ISO image. in the root directory of the backup files. Then use the mkisofs command line option -b to specify tomsrtbt-2.0.103.ElTorito.288.img as the boot image file. The only down side of this process is that many older BIOSes do not support 2.88 MB floppy images on CD-ROMs. Most of those will boot to a tomsrtbt floppy. An alternative is to use Syslinux. It is not dependent on a floppy diskette image, and you can build your own CD with a number of tools, such as tomsrtbt, on it. You may have to adjust the BIOS options to allow the computer to boot to CD-ROM drive. If you can't do that, either because the BIOS won't support booting to CD-ROM, or because you can't get into the BIOS, see Smart Boot Manager (SBM) as described in the Resources. One variant is to dispense with the tarballs in the first stage, and create a tarball of the entire system. When you build your restoration CD, put the monster tarball in the data directory of the CD. The scripts will pick that up and restore for you, combining the first and second stages. This eliminates a lot of the cruft related to permissions and ownership in restore.metadata and save.metadata Test your CDs on the drive you will use at restoration time. If you find you need to hack the scripts, you can copy them to /tmp, usually a RAM drive, and edit them there. The scripts will run there. As a RAM disk is volatile, be sure to save your changes before you reboot! NFS If you back up across your network to a backup server, you will have all the files on it you need. Set up the directory where you keep all your backups as an NFS export. Then, on Finnix, do the following (tab completion is very nice here): # mkdir /mnt/nfs # /etc/init.d/portmap start # mount server:/path/of/exportedfs /mnt/nfs # cd /mnt/nfs/.../bin Now restore as usual. There are several advantages to NFS for this job: You don't have to worry about space on a CD-ROM or ZIP drive. You can edit scripts on the server and they are preserved when you reboot the target. Multiple ZIP disks By splitting up the two first stage scripts, restore.metadata and save.metadata, you could spread the first stage metadata across multiple ZIP disks. Excluding From First Stage Saving There are time when you need to squeeze a few megabytes from the first stage data, especially when you are pushing the limit of your ZIP disk. The function crunch in the script save.metadata takes multiple parameters to feed to tar. It can also take the --exclude parameter. So, for example, you can exclude the samba and X11 directories under /etc like so: Why those two? Because they're hard drive space hogs and we don't need them when booting after the first stage. If you keep multiple kernels around, you can eliminate the modules for all of the kernels you won't boot to. Check your lilo.conf or /boot/grub/menu.lst to see which kernel you will use, and then check /lib/modules for module directories you can exclude. How to find more good candidates for exclusion? List the target directories with ls -alSr for individual files, and du | sort -n for directories. Another (probably neater) way to exclude directories is to put a complete list of directories into a file, then refer to it via the tar option --exclude-from=FILENAME. Initrd If your system uses an initial RAM disk, or initrd, to boot, make sure that restore.metadata creates the directory /initrd. The easiest way to do this is to ensure that it is included in the list of directories used in the directory creating loop toward the end. Your system will probably use an initrd if it boots from a SCSI drive or has root on an ext3fs partition. Check /etc/lilo.conf or /boot/grub/menu.lst to see if it calls for one. First Stage Restore Booting The first thing to do is to verify that the hardware time is set correctly. Use the BIOS setup for this. How close to exact you have to set the time depends on your applications. For restoration, within a few minutes of exact time should be accurate enough. This will allow time-critical events to pick up where they left off when you finally launch the restored system. tomsrtbt Before booting tomsrtbt, make sure your ZIP drive is installed on a parallel port, either /dev/lp0 or /dev/lp1. The start-up software will load the parallel port ZIP drive driver for you. The next step is to set the video mode. I usually like to see as much on the screen as I can. When the option to select a video mode comes, I use mode 6, 80 columns by 60 lines. Your hardware may or may not be able to handle high resolutions like that, so experiment with it. Knoppix These instructions will probably work with other CD-ROM or USB pen Linuxes, but you may have to vary them to suit. Before booting Knoppix, make sure your ZIP drive (or substitute) is installed on a parallel port, either /dev/lp0 or /dev/lp1. Knoppix does not load the parallel port ZIP drive driver for you. Instead, use the command modprobe ppa (as root) to install it. Boot Knoppix as usual. I find it faster and more useful to boot to a console. At the boot menu, use the command knoppix 2. Then become the root user, with su -. For the password, just hit return. Finnix One option for booting Finnix is the "toram" option, which lets you move the whole kazoo into RAM. That in turn should let you load another CD, with your first stage data, into the CD drive. Restoration These instructions assume you are running tomsrtbt. If you are using a different Linux for your restore system, you may have to adjust these instructions a bit. For example, you should always run these scripts as root even if some other user gives you the requisite privileges. Once the restoration Linux has booted and you have a console, mount the ZIP drive. It is probably a good idea to mount it read only. On tomsrtbt: # mount /dev/sda1 /mnt -o ro Check to be sure it is there: # ls -l /mnt On Knoppix or Finnix, you may want to make a directory under /mnt and mount it there, like so: # mkdir /mnt/zip # mount /dev/sda1 /mnt/zip -o ro Now cd into the mounted device, and into the bin directory below it. On Finnix, for example: # cd /mnt/zip/bin The scripts assume you are in this directory, and call data files relative to it. At this point, you can run the restoration automatically or manually. Use the automated restore if you don't need to make any changes as you go along. One consideration here is whether you have multiple hard drives. If your Linux installation mounts partitions on multiple hard drives, you must mount the root partition first. This is to ensure that mount point directories are created on the partition where they belong. The script first.stage will run the scripts to mount the drives in the order in which they are created. If you have created them (in the script save.metadata) in the order in which they cascade from root, the mounting process should work just fine. If you have multiple hard drives, and they cross-mount, you are on your own. Either combine and edit the scripts to mount them in the correct order, or do it manually. Automated The automatic process calls each of the manual scripts in proper order. It does not allow for manual intervention, say for creating file systems that this HOWTO does not support. To run the first stage restore automatically, enter the command: # first.stage If you want to check for back blocks, add the -c option. Manually Run the script(s) that will restore the partition information and create file systems. You may run them in any order, so long as they build dependencies in the correct order. You can read the script first.stage to get an idea of the order. e.g.: # ./make.dev.hda If you want to check for back blocks, add the -c option. This script will: Clean out the first 1024 bytes of the hard drive, killing off any existing partition table and master boot record (MBR). Recreate the non-LVM partitions from the information gathered when you ran make.fdisk. Make ext2 and ext3 file systems on non-LVM partitions and Linux swap partitions as appropriate. If you provide the -c option to the script, it will also check for bad blocks. Make some types of FAT partitions. Now is a good time to check the geometry of the drive. Sometimes different versions of Linux pick up different geometries, so the geometry implicit in the file dev.hdX is incorrect. To force it to be correct on Knoppix, edit make.dev.x. Use the -C, -H and -S options to fdisk to specify the cylnders, heads and sectors, respectively. Those you can get from the file fdisk.hdX in the root directory of the ZIP drive. Then re-run it. NOTEIf you have other operating systems or file systems to restore, now is a good time to do so. When you've done that, reboot to your restoration Linux and continue your first stage restoration. If you have LVM volumes to restore, now is the time to run make.lvs and mount.lvs. Now run the script(s) that create mount points and mount the partitions to them. # ./mount.dev.hda Once you have created all your directories and mounted partitions to them, you can run the script restore.metadata. # ./restore.metadata This will restore the contents of the ZIP drive to the hard drive to give you a minimal bootable system. You should see a directory of the ZIP disk's root directory, then a list of the archive files as they are restored. Tar on tomsrtbt will tell you that tar's block size is 20, and that's fine. You can ignore it. Be sure that lilo prints out its results: That will be followed by the output from a df -m command. Finishing Touches If you normally boot directly to X, you could have some problems. To be safe, the first stage script changes the run level in /target/etc/inittab to 3. Note: different distributions use different run level schemes. 3 works on Red Hat derived distributions; it may not on others. You can now gracefully reboot. Remove the medium from your boot drive if you haven't already done so, and give the computer the three fingered salute, or its equivalent: # shutdown -r now or # reboot The computer will shut down and reboot. Second Stage Restoration As the computer reboots, go back to the BIOS and verify that the clock is more or less correct. Once you have verified the clock is correct, exit the BIOS and reboot to the hard drive. You can simply let the computer boot in its normal sequence. You will see a lot of error messages, mostly along the lines of I can't find blah! Waahhh! If you have done your homework correctly up until now, those error messages won't matter. You don't need linuxconf or apache to do what you need to do. NOTEAs an alternative, you can boot to single user mode (at the lilo prompt, enter linux single), but you will have to configure your network manually and fire up sshd or whatever daemons you need to restore your system. How you do those things is very system specific. You should be able to log into a root console (no X, no users, sorry). You should now be able to use the network, for example to NFS mount the backup of your system. If you did the two stage backup I suggested for Arkeia, you can now restore Arkeia's database and executables. You should be able to run /etc/rc.d/init.d/arkeia start and start the server. If you have the GUI installed on another computer with X installed, you should now be able to log in to Arkeia on your tape server, and prepare your restoration. NOTE When you restore, read the documentation for your restoration programs carefully. For example, tar does not normally restore certain characteristics of files, like suid bits. File permissions are set by the user's umask. To restore your files exactly as you saved them, use tar's p option. Similarly, make sure your restoration software will restore everything exactly as you saved it. To restore the test computer: bash# restore.all If you used tar for your backup and restoration, and used the -k (keep old files, don't overwrite) option, you will see a lot of this: This is normal, as tar is refusing to overwrite files you restored during the first stage of restoration. Then reboot. On the way down, you will see a lot of error messages, such as no such pid. This is a normal part of the process. The shutdown code is using the pid files from daemons that were running when the backup was made to shut down daemons that were not started on the last boot. Of course there's no such pid. Your system should come up normally, with a lot fewer errors than it had before; ideally no errors. The acid test of how well your restore works on an RPM based system is to verify all packages. During the first stage backup, a verification was performed on the system, producing the file rpmVa.txt. Verify your system again, and compare the results to the one made earlier. E.g.: bash# rpm -Va | sort +2 -t ' ' | uniq > ~/foo.txt diff /mnt/zip/metadata/rpmVa.txt ~/foo.txt Prelinking error messages are normal and you can ignore them. Do not first run the command /etc/cron.daily/prelink to remove them. Doing so may introduce new errors in the verification results that will skew your results. Some files, such as configuration and log files, will have changed in the normal course of things, and you should be able to mentally filter those out of the report. Emacs users should check out its ediff facilities. Now you should be up and running. It is time to test your applications, especially those that run as daemons. The more sophisticated the application, the more testing you may need to do. If you have remote users, disable them from using the system, or make it read only while you test it. This is especially important for databases, to prevent making any corruption or data loss worse than it already might be. If you normally boot to X, it was disabled as part of the first stage restoration. Test X before you re-enable it. Re-enable it by changing that one line in /etc/inittab. Find the line that looks like this: and change it to this: Or just run this on the target to change it back. Note: different distributions use different run level schemes. These values work on Red Hat derived distributions; they may not on others. sed -i s/id:.:initdefault:/id:5:initdefault:/g /etc/inittab You should now be ready for rock and roll -- and some aspirin and a couch. Distribution Specific Notes Below are distribution notes from past experiences. If you have additional notes that you would like to add for other distributions, please forward them to me. Fedora The scripts now reflect Fedora 7, so you should not have to make any changes to these scripts. I tested the above on a fresh installation of FC3. I had problems with devices after booting when I worked with a system that had been upgraded from FC2 to FC3. Knoppix I used to use Knoppix. Pasi Oja-Nisula reports:
For me the best thing about using Knoppix is that I don't need a specific boot medium for each machine, but I can use the same tools all the time. And hardware support in Knoppix is really great. I don't have that much experience with different platforms, but all the machines I've tried have worked fine, scsi drivers are found and so on. I'm doing this recovery thing by copying the backups over the network to other machine. The restore involves booting the Knoppix cd, fetching the metadata.tar.gz from the network machine. Then make.dev, mount.dev, fetching the other tar.gz files, grub and reboot. Some typing involved but thanks to your scripts it's quite straighforward. Unless changing from ide to scsi or something, but even then it's not that difficult, since Linux is easy to restore to different hardware.
Let me add to that Knoppix detects USB devices for you, which is really nice. They make excellent (and roomier) substitutes for the ZIP drive. Also see System recovery with Knoppix. Do your restore as user root rather than as user knoppix. Otherwise you may get some directories and files owned by an oddball user or group. Also, for Knoppix, we tar the first stage stuff saving numeric user & group values instead of by name. The names may point to different numbers on knoppix, so we would be restoring the files with incorrect user and group IDs. Finnix Finnix has some of the same advantages of Knoppix. In addition, it runs in command line mode with mouse support, which is great for the task at hand. It's small, under 100 MB as of this writing, so you can remaster it with your first stage data on it. It boots quickly. And it has LVM support. And Zile, a subset of Emacs. I am pleased with Finnix for this use, and it is now my standard first stage restoration Linux. Application Specific Notes Here are some notes about backing up particular applications. Logical Volume Manager Handling logical volumes turns out to be a bit of a trick: use the Finnix distribution's startup code to turn LVM on and off. This results in distribution specific code for the first stage of restoration. It is generated in make.fdisk. To edit it, search make.fdisk for Hideous. LVM required the addition of two new LVM specific scripts, make.lvs and mount.lvs. They are only generated and used if there are logical volumes present. Selinux Selinux is disabled on the test machines. /selinux is not backed up in any of these scripts. At a guess, you should probably disable selinux after the first stage restoration, and you will probably have some selinux specific tasks to perform before turning it back on. GRUB The default bootloader in Fedora is the Grand Unified Bootloader (GRUB). It has to run at the end of the first stage, or you won't be able to boot thereafter. To preserve it for first stage restoration, make the following changes: Edit the penultimate stanza of restore.metadata: Add the following stanza to save.metadata: Tripwire If you run Tripwire or any other application that maintains a database of file metadata, rebuild that database immediately after restoring. Squid Squid is a HTTP proxy and cache. As such it keeps a lot of temporary data on the hard drive. There is no point in backing that up. Insert --exclude /var/spool/squid into the appropriate tar command in your second stage backup script. Then, get squid to rebuild its directory structure for you. Tack onto the tail end of the second stage restore script a command for squid to initialize itself. Here is how I did it over SSH in restore: The last command creates a file of length 0 called .OPB_NOBACKUP. This is for the benefit of Arkeia, and tells Arkeia not to back up below this directory Arkeia These notes are based on testing with Arkeia 4.2. Arkeia is a backup and restore program that runs on a wide variety of platforms. You can use Arkeia as part of a bare metal restoration scheme, but there are two caveats. The first is probably the most problematic, as absent any more elegant solution you have to hand select the directories to restore in the navigator at restoration time. The reason is that, apparently, Arkeia has no mechanism for not restoring files already present on the disk, nothing analogous to tar's -p option. If you simply allow a full restore, the restore will crash as Arkeia over-writes a library which is in use at restore time, e.g. lib/libc-2.1.1.so. Hand selection of directories to restore is at best dicey, so I recommend against it. The second caveat is that you have to back up the Arkeia data dictionary and/or programs. To do that, modify the save.metatdata script by adding Arkeia to the list of directories to save: $zip/arkeia.tar.gz]]> You must back up the data dictionary this way because Arkeia does not back up the data dictionary. This is one of my complaints about Arkeia, and I have solved it in the past by saving the data dictionary to tape with The TOLIS Group's BRU. The data dictionary will be restored in the script restore.metadata automatically. Amanda Amanda (The Advanced Maryland Automatic Network Disk Archiver) works quite well with this set of scripts. Use the normal Amanda back-up process, and build your first stage data as usual. Amanda stores the data on tape in GNU tar or cpio format, and you can recover from individual files to entire backup images. The nice thing about recovering entire images is that you can then use variants on the scripts in this HOWTO to restore from the images, or direct from tape. I was able to restore my test machine with the directions from W. Curtis Preston's Unix Backup & Recovery. For more information on it, see the Resources. The Amanda chapter from the book is on line. I made two changes to the script restore. First, I changed it to accept a file name as an argument. Then, since Amanda's amrestore decompresses the data as it restores it, I rewrote it to cat the file into the pipe instead of decompressing it. The resulting line looks like this: cat $file | ssh $target "umask 000 ; cd / ; tar -xpkf - " where $file is the script's argument, the image recovered from the tape by amrestore. Since the command line arguments to tar prohibit over-writing, restore from images in the reverse of the order in which they were made. Restore most recent first. Amanda does require setting ownership by hand if you back up the amanda data directory with save.metadata. Something like: bash# chown -R amanda:disk /var/lib/amanda You can also add that line to your scripts for second state restoration, such as restore. NTFS OK, NTFS isn't an application. It is a file system used by Microsoft operating system Windows NT and its descendents, including Windows 2000 and Windows XP. You can back it up and restore to it from Linux with ntfsclone, one of the NTFS utilities in the ntfsprogs suite, available from http://www.linux-ntfs.org/. These scripts will create NTFS partitions, but will not put a file system on them. It is not clear from the docs whether ntfsclone will lay down a file system on a virgin partition or not. Some Advice for Disaster Recovery You should take your ZIP disk for each computer and the printouts you made, and place them in a secure location in your shop. You should store copies of these in your off-site backup storage location. The major purpose of off-site backup storage is to enable disaster recovery, and restoring each host onto replacement hardware is a part of disaster recovery. You should also have several restoration Linux floppies or CD-ROMS, and possibly some ZIP drives in your off-site storage as well. Also, have copies of the rescue linux distribution on several of your computers so that they back each other up. You should probably have copies of this HOWTO, with your site-specific annotations on it, with your backups and in your off-site backup storage. What Now? This HOWTO results from experiments on one computer. No doubt you will find some directories or files you need to back up in your first stage backup. I have not dealt with saving and restoring X on the first stage, nor have I touched at all on processors other than AMD or Intel. I would appreciate your feedback as you test and improve these scripts on your own computers. I also encourage vendors of backup software to document how to do a minimal backup of their products. I'd like to see the whole Linux community sleep just a little better at night. To Do Volunteers are most welcome. Check with me before you start on one of these in case someone else is working on it already. We have no way to determine the label of a swap partition. This means that there is no way to provide the swap partition's label when restoring. We could assume that a system with a single swap partition (as indicated by fdisk) has the label used in the swap partition line in /etc/fstab, but that only works on single hard drive systems, and could produce subtle errors in systems with multiple swap partitions. The work-around is to add the label by hand by re-running mkswap with the -L option on it. Sigh. A partition editor to adjust partition boundaries in the dev.hdx file. This will let users adjust partitions for a different hard drive, or the same one with different geometry, or to adjust partition sizes within the same hard drive. A GUI would probably be a good idea here. On the other tentacle, the FSF's parted looks like it will fill part of the bill. It does re-size existing partitions, but with restrictions. make.fdisk currently only recognizes some FAT partitions, not all. Add code to make.fdisk to recognize others and make appropriate instructions to rebuild them in the output files. For FAT12 or FAT16 partitions we do not format, write zeros into the partition so that Mess-DOS 6.x does not get confused. See the notes on fdisk for an explanation of the problem. Translations into other (human) languages. I've referred to Red Hat Package Manager (rpm) from time to time. What are the equivalent deb commands? Modify the first stage backup code to only save the current kernel. The Scripts See the notes in the beginning of each script for a summary of what it does. First Stage <filename>make.fdisk</filename> This script, run at backup time, creates scripts similar to make.dev.hda and mount.dev.x, below, for you to run at restore time. It also produces data files similar to dev.hda and dev.hda.sfd, below. The names of the scripts and data files produced depend on the device given this script as a parameter. Those script, run at restore time, build and mount the partitions on the hard drive. make.fdisk is called from save.metadata, below. &make.fdisk; <filename>make.dev.hda</filename> This script is a sample of the sort produced by make.fdisk, above. It uses data files like dev.hda, below. It builds partitions and puts file systems on some of them. This is the first script run at restore time. If you are brave enough to edit dev.hda or dev.hda.sfd (q.v.), say, to add a new partition, you may need to edit this script as well. If you want make.dev.hda to check for bad blocks when it puts a file system on the partitions, use a "-c" command line option. &make.dev.hda; <filename>make.lvs</filename> make.lvs is generated by make.fdisk, but only if logical volumes are present. As the name suggests, it builds the logical volumes and makes file systems on them. &make.lvs; <filename>mount.dev.hda</filename> This script is a sample of the sort produced by make.fdisk, above. It builds mount points and mounts partitions on them, making the target file system ready for restoring files. This is the second script run at restore time. If you are brave enough to edit dev.hda (q.v.), say, to add a new partition, you may need to edit this script as well. &mount.dev.hda; <filename>mount.lvs</filename> mount.lvs is generated by make.fdisk, but only if logical volumes are present. As the name suggests, it mounts the logical volumes ready for restoration. &mount.lvs; <filename>dev.hda</filename> This data file is used at restore time if sfdisk is not present on the restoration Linux. It is fed to fdisk by the script make.dev.hda. It is produced at backup time by make.fdisk. Those familiar with fdisk will recognize that each line is an fdisk command or value, such as a cylinder number. Thus, it is possible to change the partition sizes and add new partitions by editing this file. That's why the penultimate command is v, to verify the partition table before it is written. &dev.hda; <filename>dev.hda.sfd</filename> This data file is used at restore time if sfdisk is present on the restoration Linux system. It is fed to sfdisk by the script make.dev.hda. It is produced at backup time by make.fdisk. Each line represents a partition. Thus, it is possible to change the partition sizes and add new partitions by editing this file. &dev.hda.sfd; <filename>save.metadata</filename> This is the first script to run as part of the backup process. It calls make.fdisk, above. If you have a SCSI hard drive or multiple hard drives to back up, edit the call to make.fdisk appropriately. WARNING Recent kernels have incorporated a new ATA (IDE) hard drive driver, libata. Because of this, parallel ATA (PATA) drives now show up as SCSI drives, as serial ATA (SATA) have always done. However, not all rescue distributions (e.g. Finnix) use this new driver. There is a line toward the bottom of save.metadata wich very carefully replaces "/dev/sda" with "/dev/hda". Use this as a template if you have multiple IDE hard drives. Comment it out or delete it if this is not an issue for you. Note that there is no guaranteed mapping! Systems with multiple hard drives may have confusing mappings. Be sure to edit this line carefully. Check it if you add or remove a hard drive of any interface type to or from your system! N.B: if you have libata IDE drive issues, the grub-install line at the end of restore.metadata won't work. If it doesn't, use your rescue disk to do the same. Or burn and boot to the boot image that is made as part of this script. Boot to it and do the second state restore as usual. The second state restore should re-run grub-install. &save.metadata; <filename>restore.metadata</filename> This script restores metadata from the ZIP disk as a first stage restore. N.B: if you have libata IDE drive issues, the grub-install line at the end of this script won't work. If it doesn't, use your rescue disk to do the same. &restore.metadata; <filename>first.stage</filename> This script runs the entire first stage restore with no operator intervention. If you want to check for bad blocks when it puts a file system on the partitions, use a "-c" command line option. &first.stage; Second Stage These scripts run on the computer being backed up or restored. <filename>back.up.all</filename> This script saves to another computer via an NFS mount. You can adapt it to save to tape drives or other media. &back.up.all; <filename>back.up.all.ssh</filename> This script does exactly what back.up.all does, but it uses SSH instead of NFS. &back.up.all.ssh; <filename>restore.all</filename> This is the restore script to use if you backed up using back.up.all. &restore.all; <filename>restore.all.ssh</filename> This is the restoration script to use if you used back.up.all.ssh to back up. &restore.all.ssh; Backup Server Scripts The SSH scripts above have a possible security problem. If you run them on a firewall, the firewall has to have access via SSH to the backup server. In that case, a clever cracker might also be able to crack the backup server. It would be more secure to run backup and restore scripts on the backup server, and let the backup server have access to the firewall. That is what these scripts are for. These scripts backup and restore the target completely, not just the stage one backup and restore. get backs up the bare metal archive separately so that you can make a CD-ROM ir NFS mount from it. I use these scripts routinely. <filename>get</filename> &get.tester; <filename>restore</filename> &restore.tester; <filename>get.target</filename> &get.target; Miscellaneous Files <filename>install</filename> This little script just installs things and sets up a few directories. It would be a useful basis for an RPM or deb package. The placement of files is based on the Filesystem Hierarchy Standard, version 2.3, announced on January 29, 2004. &install; Resources In no particular order. These are things you might want to investigate for yourself. A listing here should not be taken as an endorsement. In fact, in many case I have not used the product and cannot comment on it. Network-booting Your Operating System describes several techniques for booting across a network, using grub and some other tricks. I haven't tried it, but I have a sneaky suspicion that with an especially trained floppy diskette, you could get your entire first stage image onto the computer to be restored. Smart Boot Manager (SBM) is an OS independent and full-featured boot manager with an easy-to-use user interface. There are some screen shots available. It is essential if your BIOS will not allow you to boot to CD-ROM and you want to use a CD-ROM based Linux for Stage 1 recovery. W. Curtis Preston's excellent Unix Backup & Recovery. This is the book that got me started on this bare metal recovery stuff. I highly recommend it; read my review. An old (2000) list of small Linux disties. tomsrtbt, The most Linux on 1 floppy disk. Tom also has links to other small disties. The Linux Documentation Project. See particularly the LILO, Linux Crash Rescue HOW-TO. The Free Software Foundation's parted for editing (enlarging, shrinking, moving) partitions. QtParted looks to do the same thing with a GUI front end. Partition Image for backing up partitions. From the web page: Partition Image is a Linux/UNIX utility which saves partitions in many formats (see below) to an image file. The image file can be compressed in the GZIP/BZIP2 formats to save disk space, and split into multiple files to be copied on removable floppies (ZIP for example), .... The partition can be saved across the network since version 0.6.0. Bacula is a GLPled backup product which has bare metal recovery code inspired in part by this HOWTO. g4u ('ghost for unix') is a NetBSD-based bootfloppy/CD-ROM that allows easy cloning of PC harddisks to deploy a common setup on a number of PCs using FTP. The floppy/CD offers two functions. First is to upload the compressed image of a local harddisk to a FTP server. Other is to restore that image via FTP, uncompress it and write it back to disk; network configuration is fetched via DHCP. As the harddisk is processed as a image, any filesystem and operating system can be deployed using g4u. We present Frisbee, a system for saving, transferring, and installing entire disk images, whose goals are speed and scalability in a LAN environment. Among the techniques Frisbee uses are an appropriately-adapted method of filesystem-aware compression, a custom application-level reliable multicast protocol, and flexible application-level framing. This design results in a system which can rapidly and reliably distribute a disk image to many clients simultaneously. For example, Frisbee can write a total of 50 gigabytes of data to 80 disks in 34 seconds on commodity PC hardware. We describe Frisbee's design and implementation, review important design decisions, and evaluate its performance. There are a number of USB key disties available. Check DistroWatch for details. CD-ROM based rescue kits. This is not intended to be an exhaustive list. If you know of one (or even something that pretends to be one), please let me know. You may find more recent information at DistroWatch. Hugo Rabson's Mondo ... creates one or more bootable Rescue CD's (or tape+floppies) containing some or all of your filesystem. In the event of catastrophic data loss, you will be able to restore from bare metal. The Crash Recovery Kit for Linux System recovery with Knoppix is a good introduction to system recovery in general, and has some useful Knoppix links. Cool Linux CD is live CD with Linux system. This used 2.4 kernel and some free and demo soft. SystemRescueCd is a linux system on a bootable cdrom for repairing your system and your data after a crash. It also aims to provide an easy way to carry out admin tasks on your computer, such as creating and editing the partitions of the hard disk. It contains a lot of system utilities (parted, partimage, fstools, ...) and basic ones (editors, midnight commander, network tools). It aims to be very easy to use: just boot from the cdrom, and you can do everything. The kernel of the system supports most important file systems (ext2/ext3, reiserfs, xfs, jfs, vfat, ntfs, iso9660), and network ones (samba and NFS). Syslinux builds boot code for floppy diskettes, CD-ROMs and Intel PXE (Pre-Execution Environment) images. It is not dependent on a floppy diskette image. You can build your own CDs with a number of tools, such as tomsrtbt, on it. In case you'd like to roll your own: Linux Live is a set of bash scripts which allows you to create [your] own LiveCD from every Linux distribution. Just install your favourite distro, remove all unnecessary files (for example man pages and all other files which are not important for you) and then download and run these scripts. The PPART CD allows you to generate system recovery bootable CD of previously saved hard disks. Timo's Rescue CD Set: This set is my approach for an easy way to generate a rescue system on a bootable cd, which can easily be adapted to the own needs. The project evolves more and more into a 'debian on cd' project, so it's not only possible to use the system as a rescuecd, it is also possible to install a whole debian system on cd. The List of Live CDs has more CD based disties. GNU Free Documentation License Version 1.1, March 2000
Copyright (C) 2000 Free Software Foundation, Inc. 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA Everyone is permitted to copy and distribute verbatim copies of this license document, but changing it is not allowed.
PREAMBLE The purpose of this License is to make a manual, textbook, or other written document "free" in the sense of freedom: to assure everyone the effective freedom to copy and redistribute it, with or without modifying it, either commercially or noncommercially. Secondarily, this License preserves for the author and publisher a way to get credit for their work, while not being considered responsible for modifications made by others. This License is a kind of "copyleft", which means that derivative works of the document must themselves be free in the same sense. It complements the GNU General Public License, which is a copyleft license designed for free software. We have designed this License in order to use it for manuals for free software, because free software needs free documentation: a free program should come with manuals providing the same freedoms that the software does. But this License is not limited to software manuals; it can be used for any textual work, regardless of subject matter or whether it is published as a printed book. We recommend this License principally for works whose purpose is instruction or reference. APPLICABILITY AND DEFINITIONS This License applies to any manual or other work that contains a notice placed by the copyright holder saying it can be distributed under the terms of this License. The "Document", below, refers to any such manual or work. Any member of the public is a licensee, and is addressed as "you". A "Modified Version" of the Document means any work containing the Document or a portion of it, either copied verbatim, or with modifications and/or translated into another language. A "Secondary Section" is a named appendix or a front-matter section of the Document that deals exclusively with the relationship of the publishers or authors of the Document to the Document's overall subject (or to related matters) and contains nothing that could fall directly within that overall subject. (For example, if the Document is in part a textbook of mathematics, a Secondary Section may not explain any mathematics.) The relationship could be a matter of historical connection with the subject or with related matters, or of legal, commercial, philosophical, ethical or political position regarding them. The "Invariant Sections" are certain Secondary Sections whose titles are designated, as being those of Invariant Sections, in the notice that says that the Document is released under this License. The "Cover Texts" are certain short passages of text that are listed, as Front-Cover Texts or Back-Cover Texts, in the notice that says that the Document is released under this License. A "Transparent" copy of the Document means a machine-readable copy, represented in a format whose specification is available to the general public, whose contents can be viewed and edited directly and straightforwardly with generic text editors or (for images composed of pixels) generic paint programs or (for drawings) some widely available drawing editor, and that is suitable for input to text formatters or for automatic translation to a variety of formats suitable for input to text formatters. A copy made in an otherwise Transparent file format whose markup has been designed to thwart or discourage subsequent modification by readers is not Transparent. A copy that is not "Transparent" is called "Opaque". Examples of suitable formats for Transparent copies include plain ASCII without markup, Texinfo input format, LaTeX input format, SGML or XML using a publicly available DTD, and standard-conforming simple HTML designed for human modification. Opaque formats include PostScript, PDF, proprietary formats that can be read and edited only by proprietary word processors, SGML or XML for which the DTD and/or processing tools are not generally available, and the machine-generated HTML produced by some word processors for output purposes only. The "Title Page" means, for a printed book, the title page itself, plus such following pages as are needed to hold, legibly, the material this License requires to appear in the title page. For works in formats which do not have any title page as such, "Title Page" means the text near the most prominent appearance of the work's title, preceding the beginning of the body of the text. VERBATIM COPYING You may copy and distribute the Document in any medium, either commercially or noncommercially, provided that this License, the copyright notices, and the license notice saying this License applies to the Document are reproduced in all copies, and that you add no other conditions whatsoever to those of this License. You may not use technical measures to obstruct or control the reading or further copying of the copies you make or distribute. However, you may accept compensation in exchange for copies. If you distribute a large enough number of copies you must also follow the conditions in section 3. You may also lend copies, under the same conditions stated above, and you may publicly display copies. COPYING IN QUANTITY If you publish printed copies of the Document numbering more than 100, and the Document's license notice requires Cover Texts, you must enclose the copies in covers that carry, clearly and legibly, all these Cover Texts: Front-Cover Texts on the front cover, and Back-Cover Texts on the back cover. Both covers must also clearly and legibly identify you as the publisher of these copies. The front cover must present the full title with all words of the title equally prominent and visible. You may add other material on the covers in addition. Copying with changes limited to the covers, as long as they preserve the title of the Document and satisfy these conditions, can be treated as verbatim copying in other respects. If the required texts for either cover are too voluminous to fit legibly, you should put the first ones listed (as many as fit reasonably) on the actual cover, and continue the rest onto adjacent pages. If you publish or distribute Opaque copies of the Document numbering more than 100, you must either include a machine-readable Transparent copy along with each Opaque copy, or state in or with each Opaque copy a publicly-accessible computer-network location containing a complete Transparent copy of the Document, free of added material, which the general network-using public has access to download anonymously at no charge using public-standard network protocols. If you use the latter option, you must take reasonably prudent steps, when you begin distribution of Opaque copies in quantity, to ensure that this Transparent copy will remain thus accessible at the stated location until at least one year after the last time you distribute an Opaque copy (directly or through your agents or retailers) of that edition to the public. It is requested, but not required, that you contact the authors of the Document well before redistributing any large number of copies, to give them a chance to provide you with an updated version of the Document. MODIFICATIONS You may copy and distribute a Modified Version of the Document under the conditions of sections 2 and 3 above, provided that you release the Modified Version under precisely this License, with the Modified Version filling the role of the Document, thus licensing distribution and modification of the Modified Version to whoever possesses a copy of it. In addition, you must do these things in the Modified Version: Use in the Title Page (and on the covers, if any) a title distinct from that of the Document, and from those of previous versions (which should, if there were any, be listed in the History section of the Document). You may use the same title as a previous version if the original publisher of that version gives permission. List on the Title Page, as authors, one or more persons or entities responsible for authorship of the modifications in the Modified Version, together with at least five of the principal authors of the Document (all of its principal authors, if it has less than five). State on the Title page the name of the publisher of the Modified Version, as the publisher. Preserve all the copyright notices of the Document. Add an appropriate copyright notice for your modifications adjacent to the other copyright notices. Include, immediately after the copyright notices, a license notice giving the public permission to use the Modified Version under the terms of this License, in the form shown in the Addendum below. Preserve in that license notice the full lists of Invariant Sections and required Cover Texts given in the Document's license notice. Include an unaltered copy of this License. Preserve the section entitled "History", and its title, and add to it an item stating at least the title, year, new authors, and publisher of the Modified Version as given on the Title Page. If there is no section entitled "History" in the Document, create one stating the title, year, authors, and publisher of the Document as given on its Title Page, then add an item describing the Modified Version as stated in the previous sentence. Preserve the network location, if any, given in the Document for public access to a Transparent copy of the Document, and likewise the network locations given in the Document for previous versions it was based on. These may be placed in the "History" section. You may omit a network location for a work that was published at least four years before the Document itself, or if the original publisher of the version it refers to gives permission. In any section entitled "Acknowledgements" or "Dedications", preserve the section's title, and preserve in the section all the substance and tone of each of the contributor acknowledgements and/or dedications given therein. Preserve all the Invariant Sections of the Document, unaltered in their text and in their titles. Section numbers or the equivalent are not considered part of the section titles. Delete any section entitled "Endorsements". Such a section may not be included in the Modified Version. Do not retitle any existing section as "Endorsements" or to conflict in title with any Invariant Section. If the Modified Version includes new front-matter sections or appendices that qualify as Secondary Sections and contain no material copied from the Document, you may at your option designate some or all of these sections as invariant. To do this, add their titles to the list of Invariant Sections in the Modified Version's license notice. These titles must be distinct from any other section titles. You may add a section entitled "Endorsements", provided it contains nothing but endorsements of your Modified Version by various parties--for example, statements of peer review or that the text has been approved by an organization as the authoritative definition of a standard. You may add a passage of up to five words as a Front-Cover Text, and a passage of up to 25 words as a Back-Cover Text, to the end of the list of Cover Texts in the Modified Version. Only one passage of Front-Cover Text and one of Back-Cover Text may be added by (or through arrangements made by) any one entity. If the Document already includes a cover text for the same cover, previously added by you or by arrangement made by the same entity you are acting on behalf of, you may not add another; but you may replace the old one, on explicit permission from the previous publisher that added the old one. The author(s) and publisher(s) of the Document do not by this License give permission to use their names for publicity for or to assert or imply endorsement of any Modified Version. COMBINING DOCUMENTS You may combine the Document with other documents released under this License, under the terms defined in section 4 above for modified versions, provided that you include in the combination all of the Invariant Sections of all of the original documents, unmodified, and list them all as Invariant Sections of your combined work in its license notice. The combined work need only contain one copy of this License, and multiple identical Invariant Sections may be replaced with a single copy. If there are multiple Invariant Sections with the same name but different contents, make the title of each such section unique by adding at the end of it, in parentheses, the name of the original author or publisher of that section if known, or else a unique number. Make the same adjustment to the section titles in the list of Invariant Sections in the license notice of the combined work. In the combination, you must combine any sections entitled "History" in the various original documents, forming one section entitled "History"; likewise combine any sections entitled "Acknowledgements", and any sections entitled "Dedications". You must delete all sections entitled "Endorsements." COLLECTIONS OF DOCUMENTS You may make a collection consisting of the Document and other documents released under this License, and replace the individual copies of this License in the various documents with a single copy that is included in the collection, provided that you follow the rules of this License for verbatim copying of each of the documents in all other respects. You may extract a single document from such a collection, and distribute it individually under this License, provided you insert a copy of this License into the extracted document, and follow this License in all other respects regarding verbatim copying of that document. AGGREGATION WITH INDEPENDENT WORKS A compilation of the Document or its derivatives with other separate and independent documents or works, in or on a volume of a storage or distribution medium, does not as a whole count as a Modified Version of the Document, provided no compilation copyright is claimed for the compilation. Such a compilation is called an "aggregate", and this License does not apply to the other self-contained works thus compiled with the Document, on account of their being thus compiled, if they are not themselves derivative works of the Document. If the Cover Text requirement of section 3 is applicable to these copies of the Document, then if the Document is less than one quarter of the entire aggregate, the Document's Cover Texts may be placed on covers that surround only the Document within the aggregate. Otherwise they must appear on covers around the whole aggregate. TRANSLATION Translation is considered a kind of modification, so you may distribute translations of the Document under the terms of section 4. Replacing Invariant Sections with translations requires special permission from their copyright holders, but you may include translations of some or all Invariant Sections in addition to the original versions of these Invariant Sections. You may include a translation of this License provided that you also include the original English version of this License. In case of a disagreement between the translation and the original English version of this License, the original English version will prevail. TERMINATION You may not copy, modify, sublicense, or distribute the Document except as expressly provided for under this License. Any other attempt to copy, modify, sublicense or distribute the Document is void, and will automatically terminate your rights under this License. However, parties who have received copies, or rights, from you under this License will not have their licenses terminated so long as such parties remain in full compliance. FUTURE REVISIONS OF THIS LICENSE The Free Software Foundation may publish new, revised versions of the GNU Free Documentation License from time to time. Such new versions will be similar in spirit to the present version, but may differ in detail to address new problems or concerns. See http://www.gnu.org/copyleft/. Each version of the License is given a distinguishing version number. If the Document specifies that a particular numbered version of this License "or any later version" applies to it, you have the option of following the terms and conditions either of that specified version or of any later version that has been published (not as a draft) by the Free Software Foundation. If the Document does not specify a version number of this License, you may choose any version ever published (not as a draft) by the Free Software Foundation. How to use this License for your documents To use this License in a document you have written, include a copy of the License in the document and put the following copyright and license notices just after the title page:
Copyright (c) YEAR YOUR NAME. Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1.1 or any later version published by the Free Software Foundation; with the Invariant Sections being LIST THEIR TITLES, with the Front-Cover Texts being LIST, and with the Back-Cover Texts being LIST. A copy of the license is included in the section entitled "GNU Free Documentation License".
If you have no Invariant Sections, write "with no Invariant Sections" instead of saying which ones are invariant. If you have no Front-Cover Texts, write "no Front-Cover Texts" instead of "Front-Cover Texts being LIST"; likewise for Back-Cover Texts. If your document contains nontrivial examples of program code, we recommend releasing these examples in parallel under your choice of free software license, such as the GNU General Public License, to permit their use in free software.