Ken Gunderson wrote:
On Fri, 2012-04-20 at 18:48 -0600, Ken Gunderson wrote:
Hello List:
I've created some arrays. For example, md2 is RAID1 created with gpt
based partitions /dev/sd[ab]1
# mdadm --misc --detail /dev/md2
/dev/md2:
Version : 1.0
Creation Time : Thu Apr 19 15:56:18 2012
Raid Level : raid1
Array Size : 262132 (256.03 MiB 268.42 MB)
Used Dev Size : 262132 (256.03 MiB 268.42 MB)
Raid Devices : 2
Total Devices : 2
Persistence : Superblock is persistent
Update Time : Fri Apr 20 09:08:11 2012
State : clean
Active Devices : 2
Working Devices : 2
Failed Devices : 0
Spare Devices : 0
Name : archiso:2
UUID : e3a5c30e:3fb61039:397992ff:6cc70600
Events : 17
Number Major Minor RaidDevice State
0 8 1 0 active sync /dev/sda1
1 8 17 1 active sync /dev/sdb1
Okay, great, that works. However, I am not able to recover from
simulated failure.
# mdadm /dev/md2 --fail /dev/sdb1
# mdadm /dev/md2 --misc --detail
/dev/md2:
Version : 1.0
Creation Time : Thu Apr 19 15:56:18 2012
Raid Level : raid1
Array Size : 262132 (256.03 MiB 268.42 MB)
Used Dev Size : 262132 (256.03 MiB 268.42 MB)
Raid Devices : 2
Total Devices : 2
Persistence : Superblock is persistent
Update Time : Fri Apr 20 15:40:10 2012
State : clean, degraded
Active Devices : 1
Working Devices : 1
Failed Devices : 1
Spare Devices : 0
Name : archiso:2
UUID : e3a5c30e:3fb61039:397992ff:6cc70600
Events : 20
Number Major Minor RaidDevice State
0 8 1 0 active sync /dev/sda1
1 0 0 1 removed
1 8 17 - faulty spare /dev/sdb1
Followed by
# mdadm /dev/md2 --remove /dev/sdb1
/dev/md2:
Version : 1.0
Creation Time : Thu Apr 19 15:56:18 2012
Raid Level : raid1
Array Size : 262132 (256.03 MiB 268.42 MB)
Used Dev Size : 262132 (256.03 MiB 268.42 MB)
Raid Devices : 2
Total Devices : 1
Persistence : Superblock is persistent
Update Time : Fri Apr 20 15:59:52 2012
State : clean, degraded
Active Devices : 1
Working Devices : 1
Failed Devices : 0
Spare Devices : 0
Name : archiso:2
UUID : e3a5c30e:3fb61039:397992ff:6cc70600
Events : 31
Number Major Minor RaidDevice State
0 8 1 0 active sync /dev/sda1
1 0 0 1 removed
I should then be able to re-add sdb1, no?
# mdadm /dev/md2 --re-add /dev/sdb1
mdadm: --re-add for /dev/sdb1 to /dev/md2 is not possible
Since man mdadm explicitly provides following as example:
"mdadm /dev/md0 -f /dev/hda1 -r /dev/hda1 -a /dev/hda1"
Let's try just adding it instead of re-adding
# mdadm /dev/md2 -a /dev/sdb1
mdadm: /dev/sdb1 reports being an active member for /dev/md2, but a --re-add fails.
mdadm: not performing --add as that would convert /dev/sdb1 in to a spare.
mdadm: To make this a spare, use "mdadm --zero-superblock /dev/sdb1" first.
I am perplexed as to why might this be? I must be missing something
pretty basic here, else I can provide additional detail as require.
Thanks for your help-- Ken
btw - I do get it that /dev/sdb1 still thinks it's an active member
of /dev/md2:
# mdadm -E /dev/sdb1
/dev/sdb1:
Magic : a92b4efc
Version : 1.0
Feature Map : 0x0
Array UUID : e3a5c30e:3fb61039:397992ff:6cc70600
Name : archiso:2
Creation Time : Thu Apr 19 15:56:18 2012
Raid Level : raid1
Raid Devices : 2
Avail Dev Size : 524264 (256.03 MiB 268.42 MB)
Array Size : 524264 (256.03 MiB 268.42 MB)
Super Offset : 524272 sectors
State : clean
Device UUID : 68d2dc69:03f902eb:9c8ca454:27bd3854
Update Time : Fri Apr 20 09:46:57 2012
Checksum : 2fa4f67c - correct
Events : 17
Device Role : Active device 1
Array State : AA ('A' == active, '.' == missing)
And that I could --zero-superblock and then add the partition back into
the array.
And also that from searching the web that others encountering this seem
to solve the issue by utilizing an write bitmap.
But from my reading of the documentation I should not have to, no?
I think the problem is in the documentation, it should tell you these things
perhaps. I confess I learned about this the easy way, since I have always used a
bitmap and not encountered this until I was testing a similar post years ago.
You might be able to --force it, but I'd rather zero the superblock myself, I
don't like using the big hammer unless there's no "right" way. I think you do
understand it, at least as well as I do.
Thanks in advance for helping me understand what's actually going on
here.
--
Bill Davidsen <davidsen@xxxxxxx>
"We have more to fear from the bungling of the incompetent than from
the machinations of the wicked." - from Slashdot
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