Hello,
I have a RAID5 array, which was created with mdadm 3.2.3
Here is one of its member's superblock:
/dev/sdl:
Magic : a92b4efc
Version : 1.2
Feature Map : 0x0
Array UUID : cc0fbdd2:0feade15:963fe546:13a072fa
Name : heimdall:0 (local to host heimdall)
Creation Time : Sun May 6 10:58:30 2012
Raid Level : raid5
Raid Devices : 8
Avail Dev Size : 3907027120 (1863.02 GiB 2000.40 GB)
Array Size : 13674590720 (13041.11 GiB 14002.78 GB)
Used Dev Size : 3907025920 (1863.02 GiB 2000.40 GB)
Data Offset : 2048 sectors
Super Offset : 8 sectors
State : clean
Device UUID : 64962294:3699d869:510bef35:9d2fd78d
Update Time : Sat May 12 17:03:28 2012
Checksum : df1714ca - correct
Events : 96
Layout : left-symmetric
Chunk Size : 512K
Device Role : Active device 6
Array State : AAAAAAA. ('A' == active, '.' == missing)
Some time ago mdadm have been upgraded to 3.2.4
So, today I have replaced failed drive, but could not add it:
mdadm --manage /dev/md0 --add /dev/sdm
mdadm: add new device failed for /dev/sdm as 8: Invalid argument
And there are lines in dmesg:
md: sdm does not have a valid v1.2 superblock, not importing!
md: md_import_device returned -22
mdadm creates new superblock on sdm:
/dev/sdm:
Magic : a92b4efc
Version : 1.2
Feature Map : 0x0
Array UUID : cc0fbdd2:0feade15:963fe546:13a072fa
Name : heimdall:0 (local to host heimdall)
Creation Time : Sun May 6 10:58:30 2012
Raid Level : raid5
Raid Devices : 8
Avail Dev Size : 3906767024 (1862.89 GiB 2000.26 GB)
Array Size : 13674590720 (13041.11 GiB 14002.78 GB)
Used Dev Size : 3907025920 (1863.02 GiB 2000.40 GB)
Data Offset : 262144 sectors
Super Offset : 8 sectors
State : clean
Device UUID : ecaaf8af:f41c6ca1:8190b6f8:37b53a06
Update Time : Sat May 12 16:46:20 2012
Checksum : 6dabb37a - correct
Events : 0
Layout : left-symmetric
Chunk Size : 512K
Device Role : spare
Array State : AAAAAAA. ('A' == active, '.' == missing)
New direve's size is equals to other drive's sizes (checked with
blockdev --getsz)
The only difference between superblocks created by diferent mdadm
versions is data offset. Old one has 2048 sector offset, new one -
262144. I think, this leads to available device size to be smaller with
new superblock and inability to add drive to the array.
Downgrading mdadm allowed me to add device into array.
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