Re: Raid question

[Aurelien Bompard <gauret free fr>]

Yuhard Ngun wrote:
> # cat /etc/raidtab
> raiddev /dev/md0
>        raid-level              1
>        nr-raid-disks           2
>        nr-spare-disks          0
>        chunk-size              4
>        persistent-superblock   1
>        device                  /dev/hda
>        raid-disk               0
>        device                  /dev/hdc
>        raid-disk               1

If you have a standard FC2 and you want to move it to RAID1, you first have
to set the first disk as being "faulty", or setting up the RAID will alter
your data. To do this, change "raid-disk 0" to "failed-disk 0"
in /etc/raidtab

Then:
- partition your hdc identically to hda (fdisk is you friend here)
- run mkraid (which will say that hda is failed, that is normal)
- format your new /dev/md0 with mkfs.ext3
- copy your existing filesystem from hda to hdc (ignoring /proc and /dev,
find / -xdev is your friend here)
- edit fstab to mount /dev/md0 on /
- edit your bootloader to set root on /dev/md0
- reboot (you may want to say a prayer before)
- if everything is ok, run raidhotadd /dev/md0 /dev/hda. This will start the
sync and erase your previous data on hda.
- change failed-disk back to raid-disk in /etc/raidtab

This is just the very big picture, I did not test it. Don't do that on an
important machine, and read stuff from the net before. It's probably
incomplete, but you get the idea.


Aurélien
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