Hello list,
I grew a RAID0 by one-disk, and it re-shaped via RAID4 as expected.
However, the component superblocks still RAID4, while /proc/mdstat,
/sys/block/md0/md/level and "mdadm -D" all indicate RAID0.
I am reluctant to stop the array, in case auto-assemble can't put it
back together. (I suppose I could create a new array, but I'd want to
be quite confident about the layout of the disks.)
Is this a bug? Should/can I re-write the superblock(s)?
# cat /proc/mdstat
Personalities : [raid0] [raid1] [raid6] [raid5] [raid4]
md0 : active raid0 sdc1[2] sdd1[0]
5860268032 blocks super 1.2 512k chunks
# cat /sys/block/md0/md/level
raid0
# mdadm -D /dev/md0
/dev/md0:
Version : 1.2
Creation Time : Fri Jan 10 13:02:25 2014
Raid Level : raid0
Array Size : 5860268032 (5588.79 GiB 6000.91 GB)
Raid Devices : 2
Total Devices : 2
Persistence : Superblock is persistent
Update Time : Sun Jan 12 20:08:53 2014
State : clean
Active Devices : 2
Working Devices : 2
Failed Devices : 0
Spare Devices : 0
Chunk Size : 512K
Number Major Minor RaidDevice State
0 8 49 0 active sync /dev/sdd1
2 8 33 1 active sync /dev/sdc1
But,
# mdadm -E /dev/sd[cd]1
/dev/sdc1:
Magic : a92b4efc
Version : 1.2
Feature Map : 0x0
Array UUID : 8f51352a:610d0ecd:a1e28ddd:86c8586c
Name : anvil.localdomain:0 (local to host anvil.localdomain)
Creation Time : Fri Jan 10 13:02:25 2014
Raid Level : raid4
Raid Devices : 3
Avail Dev Size : 5860268943 (2794.39 GiB 3000.46 GB)
Array Size : 5860268032 (5588.79 GiB 6000.91 GB)
Used Dev Size : 5860268032 (2794.39 GiB 3000.46 GB)
Data Offset : 260096 sectors
Super Offset : 8 sectors
Unused Space : before=260008 sectors, after=2959 sectors
State : clean
Device UUID : ad6e6c88:0f897bc1:1f6ec909:f599bc01
Update Time : Sun Jan 12 20:08:53 2014
Bad Block Log : 512 entries available at offset 72 sectors
Checksum : 1388a7b - correct
Events : 9451
Chunk Size : 512K
Device Role : Active device 1
Array State : AA. ('A' == active, '.' == missing, 'R' == replacing)
/dev/sdd1:
Magic : a92b4efc
Version : 1.2
Feature Map : 0x0
Array UUID : 8f51352a:610d0ecd:a1e28ddd:86c8586c
Name : anvil.localdomain:0 (local to host anvil.localdomain)
Creation Time : Fri Jan 10 13:02:25 2014
Raid Level : raid4
Raid Devices : 3
Avail Dev Size : 5860268032 (2794.39 GiB 3000.46 GB)
Array Size : 5860268032 (5588.79 GiB 6000.91 GB)
Data Offset : 260096 sectors
Super Offset : 8 sectors
Unused Space : before=260008 sectors, after=2959 sectors
State : clean
Device UUID : b3cda274:547919b1:4e026228:0a4981e7
Update Time : Sun Jan 12 20:08:53 2014
Bad Block Log : 512 entries available at offset 72 sectors
Checksum : e16a1979 - correct
Events : 9451
Chunk Size : 512K
Device Role : Active device 0
Array State : AA. ('A' == active, '.' == missing, 'R' == replacing)
Somewhat aside, I grew the array with:
"mdadm --grow /dev/md0 --raid-devices=2 --add /dev/sdc1"
I suspect I should not have used "--add". Looking at the superblock,
there is a 3rd unknown device, which I did not intend to add.
Did I convince mdadm to add two devices at the same time, sdc1 *and* a
missing device? (This surprises me a bit, in the sense that
--raid-devices=2 would pertain to the added devices, rather than the
total devices in the array.)
Or, perhaps mdadm add a "dummy" device as part of the temporary RAID4
conversion?
Thanks for any comments.
Regards,
Richard
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