Can't create snapshots - out of space?

[j4m3sm63]

I can only create snapshots on 1 LUN (LUN3) ... the others all give out of space messages. Not sure what i'm missing on this but there is ample space on most of the LUNs so i figure it should work.

this is causing me major headaches as i'm trying to replicate to another system and can't ...

any ideas?

[jamesm@ntlnas01 /]$ zpool list
NAME SIZE USED AVAIL CAP HEALTH ALTROOT
Volume0 10.9T 3.41T 7.46T 31% ONLINE /mnt

[jamesm@ntlnas01 /]$ zfs list -o space
NAME AVAIL USED USEDSNAP USEDDS USEDREFRESERV USEDCHILD
Volume0 14.6M 8.01T 0 31.4K 0 8.01T
Volume0/LUN1 1.34T 2T 0 676G 1.34T 0
Volume0/LUN2 14.6M 1.01T 0 1.01T 0 0
Volume0/LUN3 1.00T 1.00T 112K 121M 1024G 0
Volume0/LUN4 1.51T 2T 0 500G 1.51T 0
Volume0/LUN5 1.60T 2T 0 407G 1.60T 0

[root@ntlnas01] ~# zfs snapshot Volume0/LUN1@20120112-LUN1
cannot create snapshot 'Volume0/LUN1@20120112-LUN1': out of space

 

[William Grzybowski]

So I guess LUN(X) are ZVOLs right?

Here is the thing, as the zvols are block devices over ZFS they cannot store snapshots on them, but in filesystems. So, for ZVOLS the snapshots of them are stored in the parent filesystem, in this case Volume0.

That being said, you cannot create snapshots of them because Volume0 has only 14MB available, except for LUN3, which is free and the snapshot is very small (less than 14M, almost 0)

 

[j4m3sm63]

What if I dropped LUN3? Would the 1TB get reallocated to the parent and allow snapshots? It would be 1TB of space ...

 

[William Grzybowski]

Thats right

 

[j4m3sm63]

Ok thanks

Is there a way to shrink zvols instead of dumping one? I.e. shave 500G off a couple LUNs without losing data on them?

 

[William Grzybowski]

Yes, you can edit ZVOL to shrink, but be aware, you msut shrink the filesystem in the client before doing so in freenas