From 4f8caf33c75027bf6264a2174ba713205b199557 Mon Sep 17 00:00:00 2001 From: greg <> Date: Sun, 9 Mar 2003 01:06:10 +0000 Subject: [PATCH] 2003-03-08 Gregory Leblanc * Linux-RAID-FAQ.sgml: Removed, migrated to XML * Linux-RAID-FAQ.xml: Updated with new information. --- LDP/faq/docbook/Linux-RAID-FAQ.sgml | 478 ---------------------------- LDP/faq/docbook/Linux-RAID-FAQ.xml | 289 +++++++++-------- 2 files changed, 156 insertions(+), 611 deletions(-) delete mode 100644 LDP/faq/docbook/Linux-RAID-FAQ.sgml diff --git a/LDP/faq/docbook/Linux-RAID-FAQ.sgml b/LDP/faq/docbook/Linux-RAID-FAQ.sgml deleted file mode 100644 index ae5c5922..00000000 --- a/LDP/faq/docbook/Linux-RAID-FAQ.sgml +++ /dev/null @@ -1,478 +0,0 @@ - - -
- - - Linux-RAID FAQ - - - Gregory - Leblanc - -
- gleblanc (at) cu-portland.edu -
- - - - - - - v0.0.10 - 24 April 2001 - gml - - Added a new section and question about benchmarking. - - - - v0.0.9 - 9 October 2000 - gml - - Updates to the location of the patches, and a couple of other - things which I can't remember. - - - - - - - This is a FAQ for the Linux-RAID mailing list, hosted on - vger.kernel.org. vger.rutgers.edu is gone, so don't bother - looking for it. It's intended as a supplement to the existing - Linux-RAID HOWTO, to cover questions that keep occurring on the - mailing list. PLEASE read this document before your post to the - list. - - - - - - - - - General - - - - Where can I find archives for the linux-raid mailing - list? - - - My favorite archives are at http://www.geocrawler.com/lists/3/Linux/57/0/. - Other archives are available at http://marc.theaimsgroup.com/?l=linux-raid&r=1&w=2 - Another archive site is http://www.mail-archive.com/linux-raid@vger.rutgers.edu/ - - - - - - Where can I find the latest version of this FAQ? - - - - The latest version of this FAQ will be available from the - LDP website at http://www.LinuxDoc.org/FAQ/. - As soon as I get my server at home fixed I'll make it available - there as well. - - - - - - - What sorts of things does this list cover? - - - - Well, obviously this list covers RAID in relation to - Linux. Most of the discussions are related to the raid code - that's been built into the Linux kernel. There are also a few - discussions on getting hardware based RAID controllers working - using Linux as the operating system. Any and all of these - discussions are valid for this list. - - - - - - - - - Kernel - - - - - I'm running [insert your linux distribution - here]. Do I need to patch my kernel to make RAID - work? - - - - Well, the short answer is, it depends. Some distributions - are using the RAID 0.90 patches, while others leave the kernel - with the older md code. Unfortunately, I don't have a list of - which distributions have which kernels. If you'd like to - maintain such a list, please email me - <gleblanc@cu-portland.edu> as well as the - linux-raid mailing list. - - If you download a 2.2.x kernel from ftp.kernel.org, then you - will need to patch your kernel. - - - - - - - How can I tell if I need to patch my kernel? - - - - That depends on which kernel series you're using. If - you're using the 2.4.x kernels, then you've already got the - latest RAID code that's available. If you're running 2.2.x, see - the following instructions on how to find out. - - The easiest way is to check what's in - /proc/mdstat. Here's a sample from a 2.2.x - kernel, with the RAID patches applied. - - - -[gleblanc@grego1 gleblanc]$ cat /proc/mdstat -Personalities : [linear] [raid0] [raid1] [raid5] [translucent] -read_ahead not set -unused devices: <none> - - -If the contents of /proc/mdstat looks like the - above, then you don't need to patch your kernel. The - "Personalities" line in your kernel may not look exactly like the - above, if you have RAID compiled as modules. Most distributions - will have RAID compiled as modules to save space on the boot - diskette. If you're not using any RAID sets, then you will - probably see a blank space at the end of the "Personalities" - line, don't worry, that just means that the RAID modules aren't - loaded yet. - - Here's a sample from a 2.2.x kernel, - without the RAID patches applied. - - - -[root@serek ~]# cat /proc/mdstat -Personalities : [1 linear] [2 raid0] -read_ahead not set -md0 : inactive -md1 : inactive -md2 : inactive -md3 : inactive - - - -If your /proc/mdstat looks like this -one, then you need to patch your kernel. - - - - - - - - - Where can I get the latest RAID patches for my kernel? - - - - The patches for the 2.2.x kernels up to, and including, - 2.2.13 are available from ftp.kernel.org. - Use the kernel patch that most closely matches your kernel - revision. For example, the 2.2.11 patch can also be used on - 2.2.12 and 2.2.13. - - The patches for 2.2.14 and later kernels are at http://people.redhat.com/mingo/raid-patches/. - Use the right patch for your kernel, these patches haven't - worked on other kernel revisions yet. Please use something like - wget/curl/lftp to retrieve this patch, as it's easier on the - server than using a client like Netscape. Downloading patches - with Lynx has been unsuccessful for me; wget may be the easiest - way. - - These patches should also be available from - - ftp://ftp.kernel.org/pub/linux/kernel/people/mingo/raid-patches/ - I could not find them on my local mirror, but please check - yours before using the main kernel.org site. You can find a - list of the local mirrors at http://www.kernel.org/mirrors/. - - - - - - - - - - How do I apply the patch to a kernel that I just - downloaded from ftp.kernel.org? - - - - - First, unpack the kernel into some directory, generally - people use /usr/src/linux. - Change to this directory, and type patch -p1 < - /path/to/raid-version.patch. - - - - On my RedHat 6.2 system, I decompressed the 2.2.16 kernel - into /usr/src/linux-2.2.16. From - /usr/src/linux-2.2.16, I - type in patch -p1 < - /home/gleblanc/raid-2.2.16-A0. - Then I rebuild the kernel using make - menuconfig and related builds. - - - - - - - - - - - - What kind of drives can I use RAID with? Do only SCSI or - IDE drives work? Do I need different patches for different kinds - of drives? - - - - Software RAID works with any block device in the Linux - kernel. This includes IDE and SCSI drives, as well as most - harware RAID controllers. There are no different patches for IDE - drives vs. SCSI drives. - - - - - - - RAIDtools - - - - - Why are the RAIDtools at http://people.redhat.com/mingo/raid-patches/ - labeled dangerous, and if they're dangerous, - should I use them? - - - - The tools are labeled dangerous - because the RAID code isn't part of the stable - Linux kernel. The tools found at the above URL are - the latest and greatest. You should use - these tools with the kernel patches from the same - location. - - - - - - - - Are there any tools other than the - dangerous ones available? - - - - No, the dangerous tools available from - http://people.redhat.com/mingo/raid-patches/ - are the most current tools to use. Everyone using - RAID with the patches at the above location should be using - these dangerous tools. - - - - - - - - Disk Failures and Recovery - - - - - How can I tell if one of the disks in my RAID array has - failed? - - - - A couple of things should indicate when a disk has failed. - There should be quite a few messages in - /var/log/messages indicating errors - accessing that device, which should be a good indication that - something is wrong. You should also notice that your - /proc/mdstat looks different. Here's a snip - from a good /proc/mdstat - - - -[gleblanc@grego1 gleblanc]$ cat /proc/mdstat -Personalities : [linear] [raid0] [raid1] [raid5] [translucent] -read_ahead not set -md0 : active raid1 sdb5[0] sda5[1] 32000 blocks [2/2] [UU] -unused devices: <none> - - - - And here's one from a /proc/mdstat - where one of the RAID sets has a missing disk. - - - -[gleblanc@grego1 gleblanc]$ cat /proc/mdstat -Personalities : [linear] [raid0] [raid1] [raid5] [translucent] -read_ahead not set -md0 : active raid1 sdb5[0] sda5[1] 32000 blocks [2/1] [U_] -unused devices: <none> - - - - I don't know if /proc/mdstat will - reflect the status of a HOT SPARE. If you have set one up, you - should be watching /var/log/messages for any - disk failures. I'd like to get some logs of a disk failure, and - /proc/mdstat from a system with a hot - spare. - - - - - - - - So my RAID set is missing a disk, what do I do now? - - - - RAID generally doesn't mark a disk as bad unless it is, so - you probably need a new disk. Most disks have a 3 year warranty, - but some good SCSI hard drives may have a 5 year warranty. See - if you can get the manufacturer to replace the failed disk for - you. When you get the new disk, power down the - system, and install it, then partition the drive so that it has - partitions the size of your missing RAID partitions. After - you're finished partitioning the disk, use the command - raidhotadd to put the new disk into the array - and begin reconstruction. See Chapter - 6 of the Software - RAID HOWTO for more information. - - - - - - - - - dmesg shows md: serializing - resync, md4 has overlapping physical units with md5. - What does this mean? - - - - In that message physical units refers to - disks, and not to blocks on the disks. Since there is more than - 1 RAID array that needs resyncing on a disk, the RAID code is - going to sync md4 first, and md5 second, to avoid excessive seeks - (also called thrashing), which would drastically slow the resync - process. - - - - - - - - Benchmarking - - - - - How should I benchmark my RAID devices? Are there any - tools that work particularly well? - - - - There are really a few options for benchmarking your RAID - array, depending on what you're looking to test. RAID offers the - greatest speed increases when there are multiple threads reading - from the same RAID volume. - - One tool specificly designed to test and show off these - performance gains is tiobench. It uses - multiple read and write threads on the disk, and has some pretty - good reporting. - - Another good tool to use is bonnie++. It - seems to be more targeted at benchmarking single drives that at - RAID, but still provides useful information. - - One tool NOT to use is - hdparm. It does not give useful - performance numbers for any drives that I've heard about, and has - been known to give some incredibly off-the-wall numbers as well. - If you want to do real benchmarking, use - one of the tools listed above. - - - - - - - - - -
- - - diff --git a/LDP/faq/docbook/Linux-RAID-FAQ.xml b/LDP/faq/docbook/Linux-RAID-FAQ.xml index ae5c5922..ecfa28ca 100644 --- a/LDP/faq/docbook/Linux-RAID-FAQ.xml +++ b/LDP/faq/docbook/Linux-RAID-FAQ.xml @@ -1,22 +1,36 @@ - +
- + Linux-RAID FAQ Gregory Leblanc - -
- gleblanc (at) cu-portland.edu -
- + gleblanc@linuxweasel.com + + v0.0.12 + 2003-03-05 + gml + Fleshed out questions that cover using mdadm, small formatting + changes + + + + v0.0.11 + 2003-01-08 + gml + Updated Archive Locations, information on when to patch, added + a note about old patches being missing, removed question about the + raidtools being dangerous (since they don't appear to be so labeled any + longer). + + v0.0.10 24 April 2001 @@ -25,15 +39,6 @@ Added a new section and question about benchmarking. - - v0.0.9 - 9 October 2000 - gml - - Updates to the location of the patches, and a couple of other - things which I can't remember. - - @@ -47,29 +52,71 @@ - + - + Linux RAID FAQ Copyright - - General + This documentation was developed for the Linux Documentation Project + by Gregory Leblanc. - - + Redistribution and use in source (XML DocBook) and 'compiled' forms + (XML, HTML, PDF, PostScript, RTF and so forth) with or without + modification, are permitted provided that the following conditions are + met: + + + + Redistributions of source code (XML DocBook) must + retain the above copyright notice, this list of conditions + and the following disclaimer as the first lines of this file + unmodified. + + + + Redistributions in compiled form (transformed to other + DTDs, converted to PDF, PostScript, RTF and other formats) + must reproduce the above copyright notice, this list of + conditions and the following disclaimer in the documentation + and/or other materials provided with the + distribution. + + + + + THIS DOCUMENTATION IS PROVIDED BY THE GREGORY LEBLANC "AS IS" AND + ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE + IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR + PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL NETWORKS ASSOCIATES + TECHNOLOGY, INC BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, + EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, + PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR + PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF + LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING + NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS + DOCUMENTATION, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. + + + + + + + + + General + + + Where can I find archives for the linux-raid mailing list? + - My favorite archives are at http://www.geocrawler.com/lists/3/Linux/57/0/. - Other archives are available at The only archives left seem to be available at http://marc.theaimsgroup.com/?l=linux-raid&r=1&w=2 - Another archive site is http://www.mail-archive.com/linux-raid@vger.rutgers.edu/ - + Where can I find the latest version of this FAQ? @@ -77,14 +124,12 @@ The latest version of this FAQ will be available from the LDP website at http://www.LinuxDoc.org/FAQ/. - As soon as I get my server at home fixed I'll make it available - there as well. + url="http://www.tldp.org/FAQ/">http://www.tldp.org/FAQ/. - + What sorts of things does this list cover? @@ -102,12 +147,10 @@ - - + Kernel - - + I'm running [insert your linux distribution here]. Do I need to patch my kernel to make RAID @@ -115,21 +158,16 @@ - Well, the short answer is, it depends. Some distributions - are using the RAID 0.90 patches, while others leave the kernel - with the older md code. Unfortunately, I don't have a list of - which distributions have which kernels. If you'd like to - maintain such a list, please email me - <gleblanc@cu-portland.edu> as well as the - linux-raid mailing list. + At this point, most major distributions are shipping with a 2.4 + based kernel, which already includes the necessary patches. If your + distribution is still using a 2.2.x kernel, upgrade! If you download a 2.2.x kernel from ftp.kernel.org, then you will need to patch your kernel. - - + How can I tell if I need to patch my kernel? @@ -179,13 +217,10 @@ md3 : inactive If your /proc/mdstat looks like this one, then you need to patch your kernel. - - - - + Where can I get the latest RAID patches for my kernel? @@ -196,46 +231,37 @@ one, then you need to patch your kernel. url="ftp://ftp.kernel.org/pub/linux/daemons/raid/alpha/">ftp.kernel.org. Use the kernel patch that most closely matches your kernel revision. For example, the 2.2.11 patch can also be used on - 2.2.12 and 2.2.13. + 2.2.12 and 2.2.13. + These patches are no longer available + from this location! I haven't been able to find the new location for + them, please email me if you know where they've gone. + + The patches for 2.2.14 and later kernels are at http://people.redhat.com/mingo/raid-patches/. Use the right patch for your kernel, these patches haven't - worked on other kernel revisions yet. Please use something like + worked on other kernel revisions. Please use something like wget/curl/lftp to retrieve this patch, as it's easier on the server than using a client like Netscape. Downloading patches with Lynx has been unsuccessful for me; wget may be the easiest - way. - - These patches should also be available from - - ftp://ftp.kernel.org/pub/linux/kernel/people/mingo/raid-patches/ - I could not find them on my local mirror, but please check - yours before using the main kernel.org site. You can find a - list of the local mirrors at http://www.kernel.org/mirrors/. - - - + way. - - + How do I apply the patch to a kernel that I just downloaded from ftp.kernel.org? - First, unpack the kernel into some directory, generally people use /usr/src/linux. Change to this directory, and type patch -p1 < /path/to/raid-version.patch. - On my RedHat 6.2 system, I decompressed the 2.2.16 kernel into /usr/src/linux-2.2.16. From @@ -247,13 +273,10 @@ one, then you need to patch your kernel. - - - - + What kind of drives can I use RAID with? Do only SCSI or IDE drives work? Do I need different patches for different kinds @@ -270,54 +293,45 @@ one, then you need to patch your kernel. - - RAIDtools + + RAID tools - + - Why are the RAIDtools at http://people.redhat.com/mingo/raid-patches/ - labeled dangerous, and if they're dangerous, - should I use them? + What tools are available for dealing with my Linux Software RAID + arrays? - The tools are labeled dangerous - because the RAID code isn't part of the stable - Linux kernel. The tools found at the above URL are - the latest and greatest. You should use - these tools with the kernel patches from the same - location. + There are currently two sets of tools available. Both sets work + quite well, and have essentially the same functionalty. I recommend the + newer set of tools, because they're much easier to use, but I'll mention + where to get the older tools as well. + + The new set of tools is called mdadm. + It doesn't have much of a homepage, but you can download tarballs and + RPMs from http://www.cse.unsw.edu.au/~neilb/source/mdadm/. + I suggest that anyone who isn't already familar with the 'raidtools' + package use these (and in fact, I suggest that folks who already know the + raidtools package switch over to these). + + The older set of tools is called + raidtools. They're available from http://people.redhat.com/mingo/raidtools/. + I believe there are other locations available, since Red Hat Linux is + shipping based on a tarball numbered 1.00.3, which I can't find online. + If anybody knows where these are, please let me know. - - - - - - - Are there any tools other than the - dangerous ones available? - - - - No, the dangerous tools available from - http://people.redhat.com/mingo/raid-patches/ - are the most current tools to use. Everyone using - RAID with the patches at the above location should be using - these dangerous tools. - - - + Disk Failures and Recovery - - + How can I tell if one of the disks in my RAID array has failed? @@ -365,58 +379,69 @@ unused devices: <none> - - + So my RAID set is missing a disk, what do I do now? - RAID generally doesn't mark a disk as bad unless it is, so - you probably need a new disk. Most disks have a 3 year warranty, - but some good SCSI hard drives may have a 5 year warranty. See - if you can get the manufacturer to replace the failed disk for - you. When you get the new disk, power down the - system, and install it, then partition the drive so that it has - partitions the size of your missing RAID partitions. After - you're finished partitioning the disk, use the command - raidhotadd to put the new disk into the array - and begin reconstruction. See Software-RAID generally doesn't mark a disk as bad unless it is, so + you probably need a new disk. Most decent quality disks have a 3 year + warranty, but some exceptional (and expensive) SCSI hard drives may have + wararnties as long as 5 years, or even longer. More and more hard drive + vendors are giving a 1 year warranty on their "consumer" drives. I + suggest avoiding any drive with a 1 year warranty if at all possible. + Try to have the manufacturer replace the failed disk if it's still under + warranty. + + When you get the new disk, power down the system, and install it, + then partition the drive so that it has partitions the size of your + missing RAID partitions. Once you have the partitions set up properly, + just run mdadm --add /dev/md0 + /dev/hdc1, where + /dev/md0 is the RAID array you're adding the + partition to, and /dev/hdc1 is the partition + that you're trying to add. Reconstruction should start + immediately. + + If you would prefer to use the RAIDtools suite, you can use the + command raidhotadd to put the new disk into the array + and begin reconstruction. See Chapter 6 of the Software RAID HOWTO for more information. - - + - dmesg shows md: serializing - resync, md4 has overlapping physical units with md5. - What does this mean? + dmesg shows md: serializing resync, + md4 has overlapping physical units + with md5 (where md4 and md5 are two + of your software RAID devices). What does this mean? In that message physical units refers to disks, and not to blocks on the disks. Since there is more than - 1 RAID array that needs resyncing on a disk, the RAID code is - going to sync md4 first, and md5 second, to avoid excessive seeks - (also called thrashing), which would drastically slow the resync - process. + one RAID array that needs resyncing on one of the disks in use for your + RAID arrays, the RAID code is going to sync md4 first, and md5 second, to + avoid excessive seeks (also called thrashing), which would drastically + slow the resync process. - - + + Benchmarking - + How should I benchmark my RAID devices? Are there any tools that work particularly well? @@ -447,9 +472,7 @@ unused devices: <none> been known to give some incredibly off-the-wall numbers as well. If you want to do real benchmarking, use one of the tools listed above. - - @@ -461,7 +484,7 @@ unused devices: <none>