Volume: Volume 'data' usage exceeds __ % of size

[kokomodrums]

I've got a client with an RN312. Last night I got three email alerts, all about 20 minutes apart, that "Volume: Volume 'data' usage exceeds 80 % of size". First it was 80%, then it jumped to 90 and 95% each time.

The worst part is that I was unaware that the unit would automatically start deleting ALL of our snapshots because the disk was full. We lost about 12 months of snapshots... 😞

I can't seem to figure out how the disk is full. We have four shares, and the total space used by all 4 is around 400GB. The unit has (2) 1TB drives, with a total of ~892 GB total space. But the web interface is telling me the disk is using 727.77 GB (82%).

I went in via SSH and got this info:

root@nas-server:~# df -h
Filesystem      Size  Used Avail Use% Mounted on
rootfs          4.0G  519M  2.9G  16% /
tmpfs            10M  4.0K   10M   1% /dev
/dev/md0        4.0G  519M  2.9G  16% /
tmpfs           996M     0  996M   0% /dev/shm
tmpfs           996M   32M  964M   4% /run
tmpfs           996M     0  996M   0% /sys/fs/cgroup
tmpfs           996M     0  996M   0% /media
/dev/md127      927G  728G  165G  82% /data
/dev/md127      927G  728G  165G  82% /home
/dev/md127      927G  728G  165G  82% /apps

Can anyone help me figure out what is actually using up that space??

Also, and this is just a rant, I think it would be MUCH better if the unit would just shut itself down when it ran out of space before DELETING ALL OF OUR SNAPSHOTS :x If there's a way to enable that, PLEASE let me know!

[StephenB]

Generally the excess space is because of the snapshots.

I'd like to see better tools to manage them.

[kokomodrums]

Thanks for the reply!

Is it common for the snapshots to rather suddenly start filling up the hard drive, and then for the readynas to delete ALL the snapshots on the machine? I've seen it automatically delete old snapshots just fine, so I feel like this situation wouldn't fall under "normal operations".

I know on older devices you could specify the amount of hard drive space the snapshots can take up, I assume this option has been removed from OS 6?

[StephenB]

When you change or delete a file, the older file is placed in the snapshot. That behavior differs from older systems, and is because of the CoW nature of btrfs.

Netgear does have a pruning algorithm in place, but in my view is not quite enough.