ReadyNAS 316 - file system read only? Unusable #27793592

(not sure I logged this under the right RN model code, it's a 6-bay 316 but unable to confirm the code)

 

I've been running a 316 without fault for many years (I was jaffacake here but only account seems locked) until last weekend when I had a very odd overnight crash. There was an error on the device display but I failed to read it properly without my glasses on. It rebooted and has worked fine since until today (Wednesday) so has been running for 72+ hours without this fault so it may or not be related.

 

Now I'm in a position where I can't write to any share on my NAS. I can an "Access Denied" error each time I try. I'm unable to mount my iSCSI LUNs or create any snapshots. It's like the whole device has gone read only.

 

Excepting the LUNs which won't mount, I can read any data from any share.

 

I don't know where to begin to troubleshoot. I've downloaded logs from  the device which shows logs like:

(status.log)

[16/12/14 14:39:09 GMT] warning:snapshot:LOGMSG_SNAPSHOT_CREATE_WARN Failed to create snapshot broken for share or LUN 'iscsidownloads'.
[16/12/14 14:41:27 GMT] warning:snapshot:LOGMSG_SNAPSHOT_CLONE_WARN Snapshot 2016_12_13__09_00_22 failed to clone to share or LUN iscsidownloads.
[16/12/14 14:43:13 GMT] warning:snapshot:LOGMSG_SNAPSHOT_CREATE_WARN Failed to create snapshot test for share or LUN 'DropboxCopy'.

(volume.log)
data defrag 2016-12-12 07:00:02 2016-12-12 07:46:57 completed
data disk test 2016-12-12 12:00:02 2016-12-12 22:12:05 pass

(system.log)

Dec 14 14:45:05 BobZilla snapperd[4197]: loading 17421 failed
Dec 14 14:45:05 BobZilla snapperd[4197]: loading 17422 failed
Dec 14 14:45:05 BobZilla snapperd[4197]: loading 17423 failed
Dec 14 14:45:05 BobZilla snapperd[4197]: loading 438 failed

Dec 14 14:43:13 BobZilla snapperd[4197]: THROW: mkdir failed errno:30 (Read-only file system)
Dec 14 14:43:13 BobZilla snapperd[4197]: CAUGHT: mkdir failed errno:30 (Read-only file system)

 

(kernel.log)

Dec 14 14:45:05 BobZilla kernel: fd_do_rw() write returned -30
Dec 14 14:45:05 BobZilla kernel: fd_do_rw() write returned -30
Dec 14 14:45:05 BobZilla kernel: fd_do_rw() write returned -30

 

Any ideas? system is pretty unusable right now, even after a restart.