Remove inactive volumes to use the disk. Disk 1,2,3,4,5,6,7,8,9,10,11,12 on a RN4200V2

I have a very similar situation to avegelien and slauterman. I recently updated to firmware 6.9.1 on an RN214. Like slauterman I was able to read from SMB shares on a RAID 5 volume but not write to them. After a reboot, I now have the "No volume exists" error. In my case, all three disks in my RAID 5 pass short tests using smartctl. All of the SMART data in the logs and at the SSH console looks good. I saw these relevant lines in dmesg and the critical errors were picked up by RAIDar diagnostics:

[   22.120698] md: md127 stopped.

[   22.121803] md: bind<sdb3>

[   22.122033] md: bind<sdc3>

[   22.122267] md: bind<sda3>

[   22.124225] md/raid:md127: device sda3 operational as raid disk 0

[   22.124233] md/raid:md127: device sdc3 operational as raid disk 2

[   22.124239] md/raid:md127: device sdb3 operational as raid disk 1

[   22.125161] md/raid:md127: allocated 3240kB

[   22.125221] md/raid:md127: raid level 5 active with 3 out of 3 devices, algorithm 2

[   22.125226] RAID conf printout:

[   22.125232] --- level:5 rd:3 wd:3

[   22.125238] disk 0, o:1, dev:sda3

[   22.125243] disk 1, o:1, dev:sdb3

[   22.125248] disk 2, o:1, dev:sdc3

[   22.125403] md127: detected capacity change from 0 to 7991637573632

[   22.485486] Adding 523708k swap on /dev/md1.  Priority:-1 extents:1 across:523708k

[   22.506940] BTRFS: device label 119c1b84:data devid 1 transid 789057 /dev/md127

[   22.669799] BTRFS info (device md127): enabling auto recovery

[   22.672132] BTRFS critical (device md127): unable to find logical 68648173568 len 4096

[   22.672144] BTRFS critical (device md127): unable to find logical 68648173568 len 4096

[   22.672192] BTRFS critical (device md127): unable to find logical 68648173568 len 4096

[   22.672203] BTRFS critical (device md127): unable to find logical 68648173568 len 4096

[   22.672243] BTRFS critical (device md127): unable to find logical 68648173568 len 4096

[   22.672251] BTRFS critical (device md127): unable to find logical 68648173568 len 4096

[   22.672265] BTRFS error (device md127): failed to read chunk root

[   22.734127] BTRFS error (device md127): open_ctree failed

RAIDar diagnostics also picked up this:

2017-12-15 00:03:01: BTRFS: error (device md127) in cleanup_transaction:1856: errno=-5 IO failure

2017-12-15 00:03:00: BTRFS: error (device md127) in btrfs_commit_transaction:2233: errno=-5 IO failure (Error while writing out transaction)

Sometime after midnight on 2017-12-15 is when I noticed that I was unable to write to SMB or AFP shares.

I made a post here today but I'm not sure if it has gone through yet:

https://community.netgear.com/t5/Using-your-ReadyNAS/RN214-Firmware-6-9-1-No-Volumes-Exist/m-p/1458252