Power Outage Caused Cache Pool to become Unmountable: No File System. Panic Attack.

[arretx]

I'm not sure what to search for to solve this problem, nor exactly what to do to limit the impact if it happens again in the future, but here's the run-down:

 

We lost power a few days ago.  Today, things started to fail.  My VM's wouldn't start due to missing files, or non-existent paths in the Cache.  So, I looked into it and it appeared everything was okay except for the errors when starting the VM's.  So, I shut down and rebooted the server.  After booting, I noticed that the Cache Pool reports Unmountable: No file system.  (Yikes, that's bad.)

 

I have two 1TB SSD 970 NVMe drives in my system in what I recall to be a Raid 1 configuration and they're both part of the cache pool.  In my list of devices, I see "Pool Devices" and under that I see `Cache` and `Cache 2` for these two drives.  The FS for this pool is obviously btrfs.

 

(Sidenote: I thought that a mirrored array was supposed to show up as a single Cache drive.)

 

Steps I've Taken:

 

1. I created a mount point in my main array /mnt/user/temp/ and successfully mounted /dev/nvme1n1 to that folder and was able to read the disk.  I'm currently running rsync to duplicate everything from that disk into the main array in a temporary folder.

 

From this point, once the files have been copied, what are my next steps to restore this pool properly, as though it's being installed for the first time, and then get the data back to where it's supposed to be?

 

Thanks!

 

 

[MrGrey]

> Power Outage Caused Cache Pool to become Unmountable...

> what to do to limit the impact if it happens again in the future

 

Get a UPS and ensure *every* drive that your server expects to be there is powered and working (including unassigned devices [usb, etc.]) during a power failure/spike/brown-out, etc. Unraid will shut down well, if needed, in an extended power failure (in my experience).

 

I wish I could help with recovery stuff, but I can't. I hope everything works out.

 

MrGrey.

[arretx]

Ironically, it's already on its way.  Still copying files from the cache disk to the array...it's taking forever.  Not sure what to expect regarding re-building.  I have data backed up so I can re-create, but a copy and re-start would be much more convenient.

[JorgeB]

Please post the diagnostics.