Hi! I can't find any mention of this problem, which I suspect is self-inflicted by using a stupid chunk size of 65536 (64MB).
My raid 5 array has 4 devices. 3 are active and 1 is a spare. I want to grow it to use all 4. Array details are below.
I removed the write-intent bitmap and used:
mdadm --grow --raid-devices=4 /dev/md5
and got the error "mdadm: failed to set raid disks" and
syslog: "md/raid:md5: reshape: not enough stripes. Needed 65536".
The max value of stripe_cache_size is half of this so I can't increase it enough although I have 8GB RAM.
I realised that the chunk size is huge and is probably causing a stripe-width that's too large, and tried to reduce the chunk size to 128K with:
mdadm --grow -c 128 /dev/md5 --backup-file=/mnt/backup/chunks.bak
and got:
"mdadm: Cannot set device shape for /dev/md5" and
syslog message "md/raid:md5: reshape: not enough stripes. Needed 65536".
Is there anything else I could try? I can recreate the array from the backup if necessary.
Version and array info:
mdadm version is 3.2.5-lubuntu0.3, kernel is 3.2.0-32-generic. I have 8GB of RAM, running Mint 13 (Maya) for now.
Array details:
/dev/md5:
Version : 1.2
Creation Time : Sun Oct 21 22:05:44 2012
Raid Level : raid5
Array Size : 1904607232 (1816.38 GiB 1950.32 GB)
Used Dev Size : 952303616 (908.19 GiB 975.16 GB)
Raid Devices : 3
Total Devices : 4
Persistence : Superblock is persistent
Update Time : Sun Nov 17 16:09:40 2013
State : clean
Active Devices : 3
Working Devices : 4
Failed Devices : 0
Spare Devices : 1
Layout : left-symmetric
Chunk Size : 65536K
Name : blackbox:md5 (local to host blackbox)
UUID : 72ffa5b6:601c3c8f:cf7d0771:bb9536a5
Events : 17268
Number Major Minor RaidDevice State
0 8 2 0 active sync /dev/sda2
3 8 53 1 active sync /dev/sdd5
2 8 34 2 active sync /dev/sdc2
5 8 66 - spare /dev/sde2
This is formatted with EXT4.
Thanks for any help.
Steven Rose
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