Hello,
I have raid5 with 6 devices. One drive died, however, I hot-removed the wrong one, so raid failed.
I found on internet that this can be fixed if I re-create raid with the same configuration, but with dead drive set as 'missing'.
I saved --examinate data for all drives, and re run raid creation:
mdadm --verbose --create /dev/md1 --level=5 --raid-devices=6 /dev/sdb missing /dev/sdc /dev/sdg /dev/sdf /dev/sde
However, I can not mount md1 and looks like it contains random data. The order is correct. However, I noticed that new raid device size is different from old one.
Old working raid --examine:
/dev/sdc:
Magic : a92b4efc
Version : 1.2
Feature Map : 0x0
Array UUID : 39f653e1:515c53b4:a88a1588:0bf0fd07
Name : spire:1 (local to host spire)
Creation Time : Fri Jun 29 01:59:00 2012
Raid Level : raid5
Raid Devices : 6
Avail Dev Size : 5860531120 (2794.52 GiB 3000.59 GB)
Array Size : 14651325440 (13972.59 GiB 15002.96 GB)
Used Dev Size : 5860530176 (2794.52 GiB 3000.59 GB)
Data Offset : 2048 sectors
Super Offset : 8 sectors
State : clean
Device UUID : 93e652d6:35c69c71:501601cd:7e640042
Update Time : Sun Dec 9 19:50:50 2012
Checksum : f30bd58d - correct
Events : 128287
Layout : left-symmetric
Chunk Size : 512K
Device Role : Active device 2
Array State : ..A.AA ('A' == active, '.' == missing)
Re-created raid examine:
/dev/sdc:
Magic : a92b4efc
Version : 1.2
Feature Map : 0x0
Array UUID : 39f653e1:515c53b4:a88a1588:0bf0fd07
Name : spire:1 (local to host spire)
Creation Time : Mon Dec 10 21:04:01 2012
Raid Level : raid5
Raid Devices : 6
Avail Dev Size : 5860271024 (2794.40 GiB 3000.46 GB)
Array Size : 14650675200 (13971.97 GiB 15002.29 GB)
Used Dev Size : 5860270080 (2794.39 GiB 3000.46 GB)
Data Offset : 262144 sectors
Super Offset : 8 sectors
State : clean
Device UUID : 4d0fe5bc:c05ec2c4:68805eab:bed7ef9c
Update Time : Mon Dec 10 21:04:39 2012
Checksum : 676939cb - correct
Events : 4
Layout : left-symmetric
Chunk Size : 512K
Device Role : Active device 2
Array State : A.AAAA ('A' == active, '.' == missing)
So "Avail Dev Size" differs with re-created one being smaller for ~100MB.
What could be the reason why I can't mount re-created raid?
Idea: smartctl on one of drives shows 17 reallocated sectors:
5 Reallocated_Sector_Ct 0x0033 199 199 140 Pre-fail Always - 17
Could this be reason why re-created raid is smaller?
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