ZFS Questions

[freud-schiller]

Hi Everybody,

i´m testing FreeNAS and i have some ZFS Questions:

1. 4x1TB would give me using RaidZ Gross 3TB, right?
2. If i ran e.g. 3x250GB RaidZ and add one 500GB to the pool, then add an other two 500GB disc, can i switch the remaining 250GB step by step offline?
3. Can i delete a disc from a pool? e.g. 4x250GB, 2x500GB and one 300GB. Can i delete the 300GB disc from the pool?

Thank you and with best regards,

David

 

[jgreco]

1) Approximately, since the usable space on a "1TB" drive is more like 900GB. So figure more like 2.7TB. Don't forget that ZFS likes free space, so plan on filling that 2.7TB no more than maybe 80-85%.

2) Not quite clear on what you're trying to do. If you have a RAIDZ, you do not want to add a single drive to the pool. You'd gain 500GB but lose redundancy for anything stored on that drive. If you have three 500GB drives, make a RAIDZ vdev of them and add THAT to the pool. Then your pool consists of two RAIDZ vdevs. Life is about as optimal as possible given the varying drive sizes.

3) No. It's a feature sorely lacking in ZFS.

 

[Stephens]

1. Yes. Though it's "3TB" decimal, not binary, and ZFS will use some of that (on top of the 1 disc for parity).
2. You need to read noobsauce80's ZFS primer. It's linked to in his signature.
3. You need to read noobsauce80's ZFS primer. It's linked to in his signature.

Long story short, build what you want from the beginning and don't piecemeal.

 

[cyberjock]

Long story short, build what you want from the beginning and don't piecemeal.

+1000 - I'd say 60% of problems wouldn't occur if people followed that one rule.

See my sig too!