Update:
I backed up locally all data I cared about from the "raid5" array while it was
stuck in the state:
md127 : active raid6 sde1[3] sda1[2] sdd1[0] sdf1[1]
5860535808 blocks super 0.91 level 6, 64k chunk, algorithm 18
[5/4] [UUUU_]
[>....................] reshape = 0.0% (1/1953511936)
finish=1895.2min speed=16642K/sec
I found that the previous patch (in
https://marc.info/?l=linux-raid&m=145187378405337&w=2) of course does not apply
cleanly to the top of the current git tree. Looking through the change logs, I
found that a slightly modified version of said patch was included just before
the mdadm-3.4 release. So instead I grabbed the git repo tagged mdadm-3.4
(http://git.neil.brown.name/?p=mdadm.git;a=snapshot;h=c61b1c0bb5ee7a09bb25250e6c12bcd4d4cafb0c;sf=tgz)
and built mdadm from there.
Starting point after unmounting filesystems and a vgchange -an (md127
is a physical volume in lvm):
# mdadm --detail /dev/md127
/dev/md127:
Version : 0.91
Creation Time : Sat Dec 17 23:41:15 2011
Raid Level : raid6
Array Size : 5860535808 (5589.04 GiB 6001.19 GB)
Used Dev Size : 1953511936 (1863.01 GiB 2000.40 GB)
Raid Devices : 5
Total Devices : 4
Preferred Minor : 127
Persistence : Superblock is persistent
Update Time : Wed Apr 6 08:33:26 2016
State : clean, degraded, reshaping
Active Devices : 4
Working Devices : 4
Failed Devices : 0
Spare Devices : 0
Layout : left-symmetric-6
Chunk Size : 64K
Reshape Status : 0% complete
New Layout : left-symmetric
UUID : 31838cca:af76c356:b4981550:b0a7388d
Events : 0.184874
Number Major Minor RaidDevice State
0 8 49 0 active sync /dev/sdd1
1 8 81 1 active sync /dev/sdf1
2 8 1 2 active sync /dev/sda1
3 8 65 3 active sync /dev/sde1
8 0 0 8 removed
I stopped the array:
# mdadm --stop /dev/md127
Then tried re-assembling it (using the locally-built mdadm):
# mdadm --assemble --verbose --update=revert-reshape /dev/md127 $devices
mdadm: looking for devices for /dev/md127
mdadm: /dev/sdd1: Can only revert reshape which changes number of devices
Is the mdadm code only looking for the case where a new device was added but
the raid level was not modified? Recall, this was a 4-device raid5 that was
attempted to be converted to a 5-device raid6.
Out of curiosity, from looking at the patch Neil committed to the tree, I also
tried adding the --invalid-backup option:
# ./md127/mdadm --assemble --verbose --update=revert-reshape
--invalid-backup /dev/md127 $devices
mdadm: looking for devices for /dev/md127
mdadm: --update=revert-reshape not understood for 0.90 metadata
I see the current metadata version is something like 1.2 now? This array (now
running on a Fedora 22 system) was originally created on a much older Fedora,
at least as old as Fedora 9.
I can create a new array out of the disks and dump my data back onto it if the
array is really stuck in a state it can't get out of. Is there anything else I
should try first, or any other experiment to run?
Noah
--
To unsubscribe from this list: send the line "unsubscribe linux-raid" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
