204 lines
6.6 KiB
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204 lines
6.6 KiB
HTML
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2 Final//EN">
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<HTML>
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<META NAME="GENERATOR" CONTENT="SGML-Tools 1.0.9">
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<TITLE>Boot + Root + Raid + Lilo : Software Raid mini-HOWTO: Upgrading from non-raid to RAID1/4/5</TITLE>
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<LINK HREF="Boot+Root+Raid+LILO-5.html" REL=next>
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<LINK HREF="Boot+Root+Raid+LILO-3.html" REL=previous>
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<LINK HREF="Boot+Root+Raid+LILO.html#toc4" REL=contents>
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<A HREF="Boot+Root+Raid+LILO-5.html">Next</A>
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<A HREF="Boot+Root+Raid+LILO-3.html">Previous</A>
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<A HREF="Boot+Root+Raid+LILO.html#toc4">Contents</A>
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<HR>
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<H2><A NAME="s4">4. Upgrading from non-raid to RAID1/4/5</A></H2>
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<P>Upgrading a non-raid system to raid is fairly easy and consists
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of several discrete steps described below. The description is for a system
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with a boot partition, root partition and swap partition.
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<PRE>
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OLD disk in the existing system:
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/dev/hda1 boot, may be dos+lodlin or lilo
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/dev/hda2 root
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/dev/hda3 swap
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</PRE>
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We will add an additional disk and convert the entire system to RAID1. You
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could easily add several disks and make a RAID5 set instead using the same
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procedure.
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<P>
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<H2><A NAME="ss4.1">4.1 Step 1 - prepare a new kernel</A>
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</H2>
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<P>Download a clean kernel, raidtools-0.90 (or the most recent version), and
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the kernel patch to upgrade the kernel to 0.90 raid.
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<P>Compile and install the raidtools and READ the documentation.
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<P>Compile and install the
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kernel to support all the flavors (0/1/4/5 ?) of raid that you will be using.
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Make sure to specify autostart of raid devices in the kernel configuration.
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Test that the kernel boots properly and examine /proc/mdstat to see
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that the raid flavors you will use are supported by the new kernel.
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<P>
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<H2><A NAME="ss4.2">4.2 Step 2 - set up raidtab for your new raid.</A>
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</H2>
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<P>The new disk will be added to an additional IDE controller as the master
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device, thus becomming /dev/hdc
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<P>
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<PRE>
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/dev/hdc1 16megs -- more than enough for several kernel images
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/dev/hdc2 most of the disk
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/dev/hdc3 some more swap space, if needed. otherwise add to hdc2
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</PRE>
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<P>Change the partition types for /dev/hdc1 and /dev/hdc2 to "fd" for
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raid-autostart.
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<P>Using the <B>failed-disk</B> parameter, create a raidtab for
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the desired RAID1 configuration. The failed disk must be the last
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entry in the table.
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<P>
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<PRE>
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# example raidtab
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# md0 is the root array
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raiddev /dev/md0
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raid-level 1
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nr-raid-disks 2
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chunk-size 32
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# Spare disks for hot reconstruction
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nr-spare-disks 0
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persistent-superblock 1
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device /dev/hdc2
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raid-disk 0
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# this is our old disk, mark as failed for now
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device /dev/hda2
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failed-disk 1
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# md1 is the /boot array
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raiddev /dev/md1
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raid-level 1
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nr-raid-disks 2
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chunk-size 32
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# Spare disks for hot reconstruction
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nr-spare-disks 0
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persistent-superblock 1
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device /dev/hdc1
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raid-disk 0
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# boot is marked failed as well
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device /dev/hda1
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failed-disk 1
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</PRE>
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<P>
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<H2><A NAME="ss4.3">4.3 Create, format, and configure RAID</A>
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</H2>
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<P>Create the md devices with the commands:
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<PRE>
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mkraid /dev/md0
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mkraid /dev/md1
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</PRE>
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<P>The raid devices should be created and start. Examination of /proc/mdstat
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should show the raid personalities in the kernel and the raid devices
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running.
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<P>Format the boot and root devices with:
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<PRE>
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mke2fs /dev/md0
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mke2fs /dev/md1
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</PRE>
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Mount the new root device somewhere handy and create the /boot directory and
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mount the boot partition.
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<PRE>
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mount /dev/md0 /mnt
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mkdir /mnt/boot
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mount /dev/md1 /mnt/boot
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</PRE>
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<P>
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<H2><A NAME="ss4.4">4.4 Copy the current OS to the new raid device</A>
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</H2>
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<P>This is pretty straightforward.
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<PRE>
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cd /
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# set up a batch file to do this
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cp -a /bin /mnt
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cp -a /dev /mnt
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cp -a /etc /mnt
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cp -a (all directories except /mnt, /proc, and nsf mounts) /mnt
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</PRE>
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This operation can be tricky if you have mounted or linked other disks to
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your root file system. The example above assumes a very simple system, you
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may have to modify the procedure somewhat.
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<P>
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<H2><A NAME="ss4.5">4.5 Test your new RAID</A>
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</H2>
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<P>Make a boot floppy and rdev the kernel.
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<P>
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<PRE>
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dd if=kernal.image of=/dev/fd0 bs=2k
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rdev /dev/fd0 /dev/md0
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rdev -r /dev/fd0 0
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rdev -R /dev/fd0 1
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</PRE>
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<P>Modify the fstab on the RAID device to reflect the new mount points as
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follows:
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<PRE>
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/dev/md0 / ext2 defaults 1 1
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/dev/md1 /boot ext2 defaults 1 1
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</PRE>
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<P>Dismount the raid devices and boot the new file system to see that all works
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correctly.
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<P>
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<PRE>
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umount /mnt/boot
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umount /mnt
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raidstop /dev/md0
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raidstop /dev/md1
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shutdown -r now
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</PRE>
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<P>Your RAID system should now be up and running in degraded mode with a floppy
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boot disk. Carefully check that you transferred everything to the new raid
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system. If you mess up here without a backup, YOU ARE DEAD!
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<P>If something did not work, reboot your old system and go back and fix things
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up until you successfully complete this step.
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<P>
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<H2><A NAME="ss4.6">4.6 Integrate old disk into raid array</A>
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</H2>
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<P>Success in the previous step means that the raid array is now operational,
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but without redundancy. We must now re-partition the old drive(s) to fit
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into the new raid array. Remember that if the geometries are not the same,
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the the partition size on the old drive must be the same or larger than the
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raid partitions or they can not be added to the raid set.
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<P>Re-partition the old drive as required. Example:
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<PRE>
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/dev/hda1 same or larger than /dev/hdc1
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/dev/hda2 same or larger than /dev/hdc2
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/dev/hda3 anything left over for swap or whatever...
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</PRE>
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<P>Change the <B>failed-disk</B> parameter in the raidtab to <B>raid-disk</B> and
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hot add the new (old) disk partitions to the raid array.
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<PRE>
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raidhotadd /dev/md1 /dev/hda1
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raidhotadd /dev/md0 /dev/hda2
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</PRE>
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Examining /proc/mdstat should show one or more of the raid devices
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reconstructing the data for the new partitions. After a minute or two...
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or so, the raid arrays should be fully synchronized
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(this could take a while for a large
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partition).
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<P>
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<P>Using the procedure described in the first sections of this document, set up
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bootable raid on the new raid pair. Hang on to that boot floppy while
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setting up and testing this last step.
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<P>
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<HR>
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<A HREF="Boot+Root+Raid+LILO-5.html">Next</A>
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<A HREF="Boot+Root+Raid+LILO-3.html">Previous</A>
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<A HREF="Boot+Root+Raid+LILO.html#toc4">Contents</A>
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