RAID recovery????

[Jeffrey Ross]

Well I figured it out, actually pretty simple once you realize what's 
going on.  To recover the RAID volumes I did the following:

Boot the linux distribution CD with the command "linux rescue"  The 
system didn't find any of my partitions which is what I expected.
next I used fdisk to partition the new disk and set the partition type 
to be 0xdf (Linux Raid).  Since the /boot partition was RAID-1 I just 
had to simply format the new /boot partition as ext3 and copy the old to 
the new with dump/restore, run grub to lay down a new boot loader etc.

The fun part now began, how to recreate the other partitions which were 
stripped with RAID-5.  After much looking around I found the command 
mdadm which allows you to manipulate the RAID volumes.  At this point I 
verified my partitions with "mdadm --query /dev/sdbX" to make sure which 
partition used to belong to which RAID volume.  Once I positively 
identified the remaining members of each group I  then issued the command:

mdadm --assemble /dev/md1 /dev/sdb2 /dev/sdc2 /dev/sdd2 
That would bring the volume up with 3 of the 4 volume members, I then 
added the 4th member with the command:
mdadm /dev/md1 -a /dev/sda2

At this point the system would happily chug away rebuilding the missing 
volume member.

I repeated the above for each of the raid volumes and at that point was 
able to reload the system.

Jeff

I Wrote:
> I have a new (experimental) system that I installed software raid with.
>
> The system has 4 - identical 18GB SCSI disks and I installed the 
> partitions as follows:
>
> /, /var, /usr, /home, and swap were made by carving out identical 
> partitions out of the 4 disks and set as raid 5 with no spares
>
> The /boot partition was set raid 1 on the first two drives and set aside 
> partitions on the other two disks as spares.
>
> Now I have failed my boot disk (SCSI ID 0) and I want to restore it, 
> copying over the /boot partition and telling grub to use it wasn't that 
> difficult, however I am at a loss to recover the other filesystems 
> without being able to load "/" the system panics at boot time.
>
> What am I doing wrong?  This is a FC5 install as it came off the CD's
>
> Thanks, Jeff
>
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