I've dusted of a machine of which I want to repair an mdadm raid5 that I messed up. First the raid5 was 3 disks. A spare was added, just before one of the three started to fail. Spare one got used and failed disk was removed. Now months later, I cannot mount it correctly. The array is broken.
original build:
root# mdadm --create --metadata=1.0 --verbose /dev/md127 --chunk=512 --level=5 --raid-devices=3 /dev/sda1 /dev/sdb1 /dev/sdc1 current situation:
$ cat /proc/mdstat Personalities : md127 : inactive sdb1[1](S) sda1[0](S) 3677730784 blocks super 1.0 unused devices: <none> mdadm -D /dev/md127
sudo mdadm -D /dev/md127 /dev/md127: Version : 1.0 Raid Level : __raid0__ Total Devices : 1 Persistence : Superblock is persistent State : inactive Name : nas:127 (local to host nas) UUID : 71da073c:d1928293:6947fa19:92d8a7bd Events : 1 Number Major Minor RaidDevice - 8 17 - /dev/sdb1 output of examine for each drive
$ sudo mdadm -E /dev/sd{b,c,e}1 **/dev/sdb1**: Magic : a92b4efc Version : 1.0 Feature Map : 0x1 Array UUID : 71da073c:d1928293:6947fa19:92d8a7bd Name : nas:127 (local to host nas) Creation Time : Sun Dec 10 23:26:56 2017 Raid Level : raid5 Raid Devices : 4 Avail Dev Size : 3677730784 (1753.68 GiB 1883.00 GB) Array Size : 5516594688 (5261.03 GiB 5648.99 GB) Used Dev Size : 3677729792 (1753.68 GiB 1883.00 GB) Super Offset : 3677730800 sectors Unused Space : before=0 sectors, after=992 sectors State : clean Device UUID : e1fdc3d2:b0f117a5:11856184:17db9522 Internal Bitmap : -16 sectors from superblock Update Time : Mon Dec 18 11:48:12 2017 Bad Block Log : 512 entries available at offset -8 sectors Checksum : 54a1b1a7 - correct Events : **1** Layout : left-symmetric Chunk Size : 512K Device Role : Active device 1 Array State : AA.. ('A' == active, '.' == missing, 'R' == replacing) **/dev/sdc1**: Magic : a92b4efc Version : 1.0 Feature Map : 0x1 Array UUID : a1498410:d13b2b4a:63379f8d:c821173f Name : fileserver:127 Creation Time : Mon Jan 19 15:35:41 2015 Raid Level : raid5 Raid Devices : 4 Avail Dev Size : 3677730536 (1753.68 GiB 1883.00 GB) Array Size : 5516594688 (5261.03 GiB 5648.99 GB) Used Dev Size : 3677729792 (1753.68 GiB 1883.00 GB) Super Offset : 3677730800 sectors Unused Space : before=0 sectors, after=992 sectors State : clean Device UUID : 472f7a29:679e1f18:87ee0d4c:88b2a62b Internal Bitmap : -16 sectors from superblock Update Time : Sun Dec 10 21:09:34 2017 Bad Block Log : 512 entries available at offset -8 sectors Checksum : 68dd142f - correct Events : **1934728** Layout : left-symmetric Chunk Size : 512K Device Role : Active device 1 Array State : AAAA ('A' == active, '.' == missing, 'R' == replacing) **/dev/sde1**: Magic : a92b4efc Version : 1.0 Feature Map : 0x1 Array UUID : 71da073c:d1928293:6947fa19:92d8a7bd Name : taknas:127 (local to host taknas) Creation Time : Sun Dec 10 23:26:56 2017 Raid Level : raid5 Raid Devices : 4 Avail Dev Size : 3677730784 (1753.68 GiB 1883.00 GB) Array Size : 5516594688 (5261.03 GiB 5648.99 GB) Used Dev Size : 3677729792 (1753.68 GiB 1883.00 GB) Super Offset : 3677730800 sectors Unused Space : before=0 sectors, after=992 sectors State : clean Device UUID : ebd3b12c:975c1a0b:4653f1ed:e9788e37 Internal Bitmap : -16 sectors from superblock Update Time : Mon Dec 18 11:48:12 2017 Bad Block Log : 512 entries available at offset -8 sectors Checksum : 931a5e9d - correct Events : **1** Layout : left-symmetric Chunk Size : 512K Device Role : Active device 0 Array State : AA.. ('A' == active, '.' == missing, 'R' == replacing) thinking out loud:
It looks like the raid5 failed, went into raid0 with 2 disk, while sda1 isn't there. And in spare mode.
Also, the events counter reset for sdb1 and sde1. sdb1 seems to be in another array. I may have forgotten to remove the failing disk from the array correctly, as it thinks it consists of 4.
Not sure what to do here to repair the raid array and keep data intact.
