Mailinglist Archive: opensuse (1264 mails)

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[opensuse] mdadm raid problem
Hello:

I have this problem in openSUSE 13.2. My mdadm version is:

mdadm --version
mdadm - v3.3.1 - 5th June 2014

I have some degraded RAID1 arrays. Before adding back the failed devices
to the arrays I would like to mount the devices independently and compare
their contents.

For example:

cat /proc/mdstat
Personalities : [raid1]
md11 : active raid1 sdb11[3]
62918468 blocks super 1.0 [2/1] [U_]


md11 array runs with one device: /dev/sdb11, and it (/dev/md11) is mounted.
It's failed counterpart is /dev/sdc11.

I would like to assemble /dev/sdc11 to a new array and mount the new array.
Previously (in openSUSE 12.2, eg.) I could simply do this:

mdadm -A /dev/md101 /dev/sdc11

and it worked without problem, assembled md101 that I could mount.

But in openSUSE 13.2 (mdadm - v3.3.1) it gives error:

mdadm -A /dev/md101 /dev/sdc11
mdadm: Found some drive for an array that is already active: /dev/md/11
mdadm: giving up.

I know it means that running md11 array has the same uuid as the "would be
created" new md101 array and therefore mdadm prevents its assembly.

But how can I then assemble /dev/sdc11 to an independent array?

I tried to assemble the new array with updating the uuid:

# mdadm -A -U uuid /dev/md101 /dev/sdc11
mdadm: Found some drive for an array that is already active: /dev/md/11
mdadm: giving up.

or:

mdadm -A -U uuid -u 4ff5944f:b14c863f:9fddd970:c1ea6abc /dev/md101 /dev/sdc11
mdadm: Found some drive for an array that is already active: /dev/md/11
mdadm: giving up.

(I changed the last 3 digits of the original uuid.)


mdadm man says:

-U, --update=
Update the superblock on each device while assembling the array. lhe argument given to this flag can be one of sparc2.2, summaries, uuid,
name, homehost, resync, byteorder, devicesize, no-bitmap, bbl, no-, metadata, or super-minor.

The uuid option will change the uuid of the array. If a UUID is given with the --uuid option that UUID will be used as a new UUID and will
NOT be used to help identify the devices in the array. If no --uuid is given, a random UUID is chosen.

Even if I could assemble /dev/sdc11 with a new uuid, how can I then
add it back to md11 later? The new uuid will prevent it, I guess.
I will have to change back the uuid to the original. It is tedious
and error-prone.

What would be the best solution?

Thanks,

Istvan



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