1. RAID problems (long), someone wrote a new superblock on an old raid
Hi,
I have a little problem here I was wondering if anyone could help me with.
I went out on a work order yesterday and I ran into something I'm not quite
sure how to deal with.
Basically, someone tripped on a network cable and jerked the network card
out of the PCI bus on a dell linux server, all 4 disks in a raid 5 were
marked bad I believe.
After the raid would not come back up, the administrator upgraded the
superblocks to raid .90 compatible superblocks. I'm not sure if this worked
and the disks were still marked bad, or if it didn't work, but next the
administrator did a mkraid --force on the partition using the new raidtools.
Currently the box comes up under .90 with all disks complaining of a bad
raid superblock checksum. I do believe there is a valid .90 superblock
somewhere because mkraid --upgrade says that an upgrade is not required.
My questions:
Has any of the data on the disk been wiped to make room for the new
superblock? ie. does doing a mkraid simply write over the space of
an old raid superblock, or did the size or the format of the actual
data on the disk change?
My thoughts are to write a new .90 valid superblock to the disks and
see if there is a somewhat valid filesystem left. Do you agree that
no additional data would be lost in this circumstance? If that doesn't
work then try writing an old superblock and see what the fs looks like.
Any suggestions on a course of action to take care of this? The owner
of this box is considering sending it off to a data reconstruction
company, anything I do needs to not further compromise any more data.
Is there a way just recalculate/write checksums on the superblocks so
the drives look good again?
Last thing, if a raid superblock checksum is bad on all 4 disks, what was
likely the cause? Software misconfiguration, or something physical?
Thank you very much for any help.
--Dustin
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