I found simmilar problem here: Missing mdadm raid5 array reassembles as raid0 after powerout, but mine is a bit different.
Here too my raid5 reassembles as raid0, but i don't see any of my devices marked as spare in mdadm -E /dev/sdX1 output:
/dev/sdb1:
Magic : a92b4efc
Version : 1.2
Feature Map : 0x0
Array UUID : 9b244d41:0b94c8f7:0da323ac:f2a873ec
Name : bekap:0 (local to host bekap)
Creation Time : Wed Oct 9 16:03:25 2013
Raid Level : raid5
Raid Devices : 3
Avail Dev Size : 5860268032 (2794.39 GiB 3000.46 GB)
Array Size : 5860267008 (5588.79 GiB 6000.91 GB)
Used Dev Size : 5860267008 (2794.39 GiB 3000.46 GB)
Data Offset : 262144 sectors
Super Offset : 8 sectors
Unused Space : before=262064 sectors, after=1024 sectors
State : active
Device UUID : f8405c86:85d8bade:8a74b0f5:fec08e3f
Update Time : Sat Jan 16 04:41:05 2016
Checksum : da1a9cb2 - correct
Events : 134111
Layout : left-symmetric
Chunk Size : 512K
Device Role : Active device 0
Array State : AA. ('A' == active, '.' == missing, 'R' == replacing)
/dev/sdc1:
Magic : a92b4efc
Version : 1.2
Feature Map : 0x0
Array UUID : 9b244d41:0b94c8f7:0da323ac:f2a873ec
Name : bekap:0 (local to host bekap)
Creation Time : Wed Oct 9 16:03:25 2013
Raid Level : raid5
Raid Devices : 3
Avail Dev Size : 5860268032 (2794.39 GiB 3000.46 GB)
Array Size : 5860267008 (5588.79 GiB 6000.91 GB)
Used Dev Size : 5860267008 (2794.39 GiB 3000.46 GB)
Data Offset : 262144 sectors
Super Offset : 8 sectors
Unused Space : before=262064 sectors, after=1024 sectors
State : active
Device UUID : d704efde:067523c1:a6de1be2:e752323f
Update Time : Sat Jan 16 04:41:05 2016
Checksum : 124f919 - correct
Events : 134111
Layout : left-symmetric
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 : 9b244d41:0b94c8f7:0da323ac:f2a873ec
Name : bekap:0 (local to host bekap)
Creation Time : Wed Oct 9 16:03:25 2013
Raid Level : raid5
Raid Devices : 3
Avail Dev Size : 5860268032 (2794.39 GiB 3000.46 GB)
Array Size : 5860267008 (5588.79 GiB 6000.91 GB)
Used Dev Size : 5860267008 (2794.39 GiB 3000.46 GB)
Data Offset : 262144 sectors
Super Offset : 8 sectors
Unused Space : before=262064 sectors, after=1024 sectors
State : clean
Device UUID : c52383f7:910118d3:e808a29f:b4edad2c
Update Time : Mon Dec 28 10:46:40 2015
Checksum : d69974b5 - correct
Events : 52676
Layout : left-symmetric
Chunk Size : 512K
Device Role : Active device 2
Array State : AAA ('A' == active, '.' == missing, 'R' == replacing)
But they are marked as S (which as far as I know stands for spare) in /proc/mdstat (and there are no personalities for md0):
Personalities :
md0 : inactive sdb1[0](S) sdd1[3](S) sdc1[1](S)
8790402048 blocks super 1.2
unused devices: <none>
Here is mdadm -D /dev/md0 output:
/dev/md0:
Version : 1.2
Raid Level : raid0
Total Devices : 3
Persistence : Superblock is persistent
State : inactive
Name : bekap:0 (local to host bekap)
UUID : 9b244d41:0b94c8f7:0da323ac:f2a873ec
Events : 134111
Number Major Minor RaidDevice
- 8 17 - /dev/sdb1
- 8 33 - /dev/sdc1
- 8 49 - /dev/sdd1
So I'm a bit confused why it can't reassemble this array if it has two (I would say good devices) out of three. I'm not sure if mdadm -D /dev/md0 showed it as raid0 since the failure or if I just messed it up while trying to reassemble the array (I tried mdadm --stop /dev/md0 and mdadm --assemble --scan --verbose and mdadm --assemble --scan --verbose /dev/md0 /dev/sdb1 /dev/sdc1 or something simmilar - I can try to get exact commands if it is necessary).
So, my question: can I remove sdd1 from array, then assemble md0 without it and then add sdd1 again? Or should I use --assemble --force --run as mentioned in the linked question? Or something else? I'm quite unexperienced with linux raid and mdadm.
Thanks a lot.