dataset file redundancy setting?

[EtienneB]

Goodevening,
I am new to Freenas after using ZFSGuru for a couple of years. Within ZFSGuru I could within a dataset(filesystem) set keep file copies = 2. E.g. in my volume Tank I have a filesystem called pictures (/tank/pictures/) and have 2 copies of each file in that folder (the system keeps those extra copies on different drives).

I am unable to find this in Freenas 11.
Any ideas where I can find and set this? And where I can see which datasets have this set and also I would like to see how much space this is using in my Tank?
Thanks,
Etienne

 

[Nick2253]

If you have proper device redundancy set up, this setting is not needed.

http://jrs-s.net/2016/05/02/zfs-copies-equals-n/

 

[EtienneB]

Thanks, read it pretty clear. My volume Tank consists of 3x raidz2 pools of 6 vdevs/drives each. So have plenty of redundancy I think.

Any idea how to view and potentially reclaim space occupied by multiple copies of files? Or even see which datasets have this enabled....

 

[Nick2253]

You can use the zfs get all tank/home command to get the properties of the dataset tank/home. Replace tank/home with whatever your dataset(s) are called.

 

[danb35]

You can use the zfs get all tank/home command to get the properties of the dataset tank/home.

...or even zfs get copies pool/dataset to get that specific property. And zfs set copies=1 pool/dataset to set it back to 1. But setting that value back to 1 won't free the space consumed by the extra copies--the only way to do that would be to rewrite the data after making that change.

 

[EtienneB]

Thanks, that solved it. Found 4 out of 30 datasets. Would be nice to have that in the GUI of Freenas

 

[danb35]

Would be nice to have that in the GUI of Freenas

Perhaps, but it doesn't seem like a very useful setting if you have a proper redundant pool in the first place.

 

[droeders]

A while back I found this article that tested how much the "copies=2" property would help when there's disk corruption within a pool:

http://jrs-s.net/2016/05/09/testing-copies-equals-n-resiliency/

It can't hurt, but certainly wouldn't help me sleep at night.