I had a 3 disk raid5 with a hot spare. I ran this:
mdadm --grow /dev/md126 --level=6 --backup-file /root/r6rebuild
I suspect I should have changed the number of devices in the above command to 4.
The reshape "started" according to /proc/mdstat but never got past
block 1, and the time to complete started going up. I did stop the
array and have tried to do a revert-reshape but it indicates it will
only revert a number of devices change.
The backup-file was created on a separate ssd.
trying assemble now gets this:
mdadm --assemble /dev/md126 /dev/sd[abe]1 /dev/sdd
--backup-file=/root/r6rebuild
mdadm: Failed to restore critical section for reshape, sorry.
examine shows this (sdd was the spare when the --grow was issues)
mdadm --examine /dev/sdd
/dev/sdd1:
Magic : a92b4efc
Version : 0.91.00
UUID : 2fb920b1:ce7407fd:dd1a1aa6:74dcda71
Creation Time : Wed May 19 19:04:03 2010
Raid Level : raid6
Used Dev Size : 488384384 (465.76 GiB 500.11 GB)
Array Size : 976768768 (931.52 GiB 1000.21 GB)
Raid Devices : 4
Total Devices : 4
Preferred Minor : 126
Reshape pos'n : 0
New Layout : left-symmetric
Update Time : Mon May 22 09:25:38 2017
State : clean
Internal Bitmap : present
Active Devices : 4
Working Devices : 4
Failed Devices : 0
Spare Devices : 0
Checksum : bc406f24 - correct
Events : 6140735
Layout : left-symmetric-6
Chunk Size : 64K
Number Major Minor RaidDevice State
this 3 8 48 3 active /dev/sdd
0 0 8 17 0 active sync /dev/sdb1
1 1 8 65 1 active sync /dev/sde1
2 2 8 1 2 active sync /dev/sda1
3 3 8 48 3 active /dev/sdd
mdadm-3.4-2.fc25.x86_64
kernel 4.10.15.200 fc25 fully updated as of 2 days ago.
Examine seems to indicate that the reshape never stopped but the
revert is unable to cancel this grow even though it did not start at
all.
The data is not super critical I don't believe I lose anything as this
one is being used primarily for backups.
It does appear that I added sdd rather than sdd1 but I don't believe
that is anything critical to the issue as it should still work fine
with the entire disk.
Ideas on how to abort the reshape that never started or how to get it
to continue? The desired final target is a 4 disk raid6. I have not
as of yet rebooted.
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