RAID recovery????

[Tod Merley]

On 8/19/06, Jeffrey Ross <jeff at bubble.org> wrote:
> 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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Hi again Jeff!

Megathanks for the reply.   RAID, LVM, and EVMS are all issues that
kind of "scare" me at this point.  I guess we all get there bit by bit
(well, in today's world perhaps "byte by byte").

Glad you got it!

Tod