On Thu, Nov 28, 2002 at 08:53:59AM -0400, Shaw, Marco wrote:
> Going for my RHCE in a few weeks... Always wondered:
>
> 1. Are there any gotchas in a corrupted software RAID filesystem? For example, /dev/md0 is an RAID1 MD device, and either the 1st superblock on /dev/md0 or maybe the underlying /dev/sda1 partition is zero'ed out. How does one go about fixing it? Will a simple fsck here work? But in the above case, is fsck run against md0 or sda1?
Well, with RAID-1 you know that the underlying partitions *should*
contain identical information. So if your array is screwed, there is a
chance that one of the partitions actually contains good information.
If you array isn't running at all, try mounting the two partitions - see
which one contains good data. If any of the two are good, get a backup
of that one.
I'm sure you can assemble the array again, telling the MD code to
rebuild the array from a specific partition, using mdadm (but I can't
tell you how). Can anyone shed some light on this one ? :)
If your array is running, non-degraded, then the underlying partitions
are identical, and there is little else you can do except for fsck.
>
> 2. If one knows that /dev/md0 is in trouble (composed of /dev/sda1 and /dev/sdb1), but /dev/sda1 is fine, can one, upon boot, simply change LILO/GRUB from trying to mount root from /dev/md0 to /dev/sda1? My guess is no, since the disk label is different.
On the kernel command line, specify root=/dev/sda1 or root=/dev/sdb1 -
you can tell your boot-loader to do this.
Disk labels don't matter here.
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