These instructions are notes I made for myself. They don't include the
intricate details. This was done using Ubuntu 7.1 from the alternate
disk.
* Boot from the alternate disk
* Select 'Install in text mode' install
* Choose no on the detect keyboard layout question and enter this manually
* Choose 'Manual' partioning
* Create the partitions for the RAID sets (including the spare). Create two
partitions on the drives, one for the system and the other for the Swap. The
size of the Swap partition should be around twice the amount of RAM the machine
has.
o When creating the partitions select the use as: "physical volume
for RAID" and select bootable for the system partitions.
* Select 'Configure Software RAID' to setup the RAID sets.
o Select 'Create MD Device'
o RAID1
o Number of active devices: 2
o Number of spare devices: 1
o Select the 2 active devices
o Select the 1 spare device
o Repeat for the Swap disk
o Select Finish
* Now the RAID sets have been created we need to partition them.
o For the boot disk select use as 'Ext3 journaling file system' with
'/' as the mount point and give the disk a label if desired.
o For the Swap disk select use as 'swap area'
* Select 'Finish partitioning and write changes to disk'
* Allow the system to install and reboot.
* Login and in a terminal window enter 'cat /proc/mdstat' to display the
status of the RAID sets. The RAID sets should be sync'ing. Enter 'watch cat
/proc/mdstat' to monitor the progress of the sync. You may continue to work
whilst the RAID sets are sync'ing even though things will be a little slow.
* Check that the RAID sets have been loaded correctly. Sometimes the spare
doesn't get added correctly.
o use 'sudo mdadm --query --detail /dev/md0' to see the detail on the
status of an array (in this case /dev/md0).
o use 'sudo mdadm --add /dev/md0 /dev/sdc2' to add a drive (in this
case partition /dev/sdc2 is added to /dev/md0).
* Need to ensure that either drive will boot should the other fail. Boot
from the UBUNTU install disk and perform the following actions:
o When booting from the install CD select 'Rescue a broken system'
o Continue through the prompts until the screen 'Device to use as a
root file system' is displayed.
o Press '<alt>F2' to switch to a second console screen and press
Enter to activate it.
o Mount the md0 RAID device and use chroot and grub to install the
bootloader onto both sda and sdb using the following commands:
+ mount /dev/md0 /mnt
+ chroot /mnt
+ grub
+ device (hd0) /dev/sda
+ root (hd0,0)
+ setup (hd0)
+ device (hd1) /dev/sdb
+ root (hd1,0)
+ setup (hd1)
+ quit
o Reboot the system using '<alt>F1' to switch back to the initial
console, escape and select 'Abort the instatllation'.
Note that if the spare drive is ever needed, the above actions will need
to be performed again to load the boot system onto this spare drive.
* Check the status of the RAID sets once the system boots up again.
To ensure that the system will boot with a degraded RAID array follow
these instructions:
Edit "/usr/share/initramfs-tools/scripts/local" and find the following
comment "# We've given up, but we'll let the user fix matters if they
can".
Just before this comment add the following code:
# The following code was added to allow degraded RAID arrays to start
if [ ! -e "${ROOT}" ] || ! /lib/udev/vol_id "${ROOT}" >/dev/null 2>&1;
then
# Try mdadm and allow degraded arrays to start in case a drive
has failed
log_begin_msg "Attempting to start RAID arrays and allow
degraded arrays"
/sbin/mdadm --assemble --scan
log_end_msg
fi
Rebuild the boot image using "sudo update-initramfs -u"
Hope this helps,
Ken
--
cannot boot raid1 with only one disk
https://bugs.launchpad.net/bugs/120375
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