Recover from a clean, degraded RADI5

Good morning all,

I have some NAS software which – for the most part – works great, but when something happens to the Hyper-V host it often fails spectacularly. Today is one of those days.

I’m not great at under the hood stuff but have Google’d around and come to the conclusion the whole thing is confused! I only have one RAID5 with 7 disks in total which seems to correspond to mdadm –detail /dev/md2.

Can anyone give me any guidance on how to bring the volume back to life?

mdadm --detail /dev/md3 /dev/md3: Version : 1.2 Creation Time : Sun Apr  1 20:22:22 2018 Raid Level : raid5 Array Size : 3906971648 (3725.98 GiB 4000.74 GB) Used Dev Size : 976742912 (931.49 GiB 1000.18 GB) Raid Devices : 5 Total Devices : 4 Persistence : Superblock is persistent  Update Time : Fri Dec 21 07:52:22 2018       State : clean, degraded Active Devices : 4 Working Devices : 4 Failed Devices : 0 Spare Devices : 0  Layout : left-symmetric Chunk Size : 64K  Name : SUPERSYNO:3 UUID : e3f844f6:4bd70c27:c40439c2:8d1a29e9 Events : 12216  Number   Major   Minor   RaidDevice State 0       8       70        0      active sync   /dev/sde6 1       0        0        1      removed 4       8      150        2      active sync   /dev/sdj6 5       8      118        3      active sync   /dev/sdh6 2       8      134        4      active sync   /dev/sdi6  mdadm --detail /dev/md0 /dev/md0: Version : 0.90 Creation Time : Sat Jan  1 00:04:42 2000 Raid Level : raid1 Array Size : 2490176 (2.37 GiB 2.55 GB) Used Dev Size : 2490176 (2.37 GiB 2.55 GB) Raid Devices : 12 Total Devices : 8 Preferred Minor : 0 Persistence : Superblock is persistent  Update Time : Fri Dec 21 08:08:09 2018     State : clean, degraded Active Devices : 8 Working Devices : 8 Failed Devices : 0 Spare Devices : 0  UUID : 26aa5fea:f6cb55b4:3017a5a8:c86610be Events : 0.5720  Number   Major   Minor   RaidDevice State 0       8       33        0      active sync   /dev/sdc1 1       8       49        1      active sync   /dev/sdd1 2       8      145        2      active sync   /dev/sdj1 3       8      129        3      active sync   /dev/sdi1 4       8      113        4      active sync   /dev/sdh1 5       8       97        5      active sync   /dev/sdg1 6       8       81        6      active sync   /dev/sdf1 7       8       65        7      active sync   /dev/sde1 8       0        0        8      removed 9       0        0        9      removed 10       0        0       10      removed 11       0        0       11      removed  mdadm --detail /dev/md1 /dev/md1: Version : 0.90 Creation Time : Thu Dec 20 22:46:39 2018 Raid Level : raid1 Array Size : 2097088 (2048.28 MiB 2147.42 MB) Used Dev Size : 2097088 (2048.28 MiB 2147.42 MB) Raid Devices : 12 Total Devices : 8 Preferred Minor : 1 Persistence : Superblock is persistent  Update Time : Thu Dec 20 22:47:37 2018       State : active, degraded Active Devices : 8 Working Devices : 8 Failed Devices : 0 Spare Devices : 0  UUID : 3637e4b4:d5bb08ce:dca69c88:18a34d86 (local to host SuperSyno) Events : 0.19  Number   Major   Minor   RaidDevice State 0       8       34        0      active sync   /dev/sdc2 1       8       50        1      active sync   /dev/sdd2 2       8       66        2      active sync   /dev/sde2 3       8       82        3      active sync   /dev/sdf2 4       8       98        4      active sync   /dev/sdg2 5       8      114        5      active sync   /dev/sdh2 6       8      130        6      active sync   /dev/sdi2 7       8      146        7      active sync   /dev/sdj2 8       0        0        8      removed 9       0        0        9      removed 10       0        0       10      removed 11       0        0       11      removed  mdadm --detail /dev/md2 /dev/md2: Version : 1.2 Creation Time : Sun Apr  1 20:22:22 2018 Raid Level : raid5 Array Size : 20478048192 (19529.39 GiB 20969.52 GB) Used Dev Size : 2925435456 (2789.91 GiB 2995.65 GB) Raid Devices : 8 Total Devices : 7 Persistence : Superblock is persistent  Update Time : Thu Dec 20 22:34:47 2018       State : clean, degraded Active Devices : 7 Working Devices : 7 Failed Devices : 0 Spare Devices : 0  Layout : left-symmetric Chunk Size : 64K  Name : SUPERSYNO:2 UUID : 7d8b04cf:aebb8d01:6034359b:c4bb62db Events : 280533  Number   Major   Minor   RaidDevice State 9       8       53        0      active sync   /dev/sdd5 1       8       69        1      active sync   /dev/sde5 2       0        0        2      removed 7       8      149        3      active sync   /dev/sdj5 8       8      117        4      active sync   /dev/sdh5 5       8      133        5      active sync   /dev/sdi5 4       8      101        6      active sync   /dev/sdg5 3       8       85        7      active sync   /dev/sdf5  mdadm --detail /dev/md3 /dev/md3: Version : 1.2 Creation Time : Sun Apr  1 20:22:22 2018 Raid Level : raid5 Array Size : 3906971648 (3725.98 GiB 4000.74 GB) Used Dev Size : 976742912 (931.49 GiB 1000.18 GB) Raid Devices : 5 Total Devices : 4 Persistence : Superblock is persistent  Update Time : Fri Dec 21 08:01:56 2018       State : clean, degraded Active Devices : 4 Working Devices : 4 Failed Devices : 0 Spare Devices : 0  Layout : left-symmetric Chunk Size : 64K  Name : SUPERSYNO:3 UUID : e3f844f6:4bd70c27:c40439c2:8d1a29e9 Events : 12218  Number   Major   Minor   RaidDevice State 0       8       70        0      active sync   /dev/sde6 1       0        0        1      removed 4       8      150        2      active sync   /dev/sdj6 5       8      118        3      active sync   /dev/sdh6 2       8      134        4      active sync   /dev/sdi6