Multiple pools of mirror vdevs

Status
Not open for further replies.

ShimadaRiku

Contributor
Joined
Aug 28, 2015
Messages
104
Any problems with having multiple individual pools of mirrored vdev?

I want to start with a 2x4TB mirror vdev in a pool. Then add a separate pool with another mirrored vdev when I need more storage & so on. This way any vdev failure will not affect the other pools.

There is only 1 drive redundancy as oppose to raidz2, but failure is isolated per pool. I also lose the convenience of having a single large pool in terms of management, but I am okay with that. I'll be storing mostly replaceable data and some important stuff will be backed up else where.

My reasoning is to avoid the upfront cost of getting 6x4TB raidz2 & not fully utilizing it. By the time I do a 16TB drive would probably exist and cost less. In essence I am trading extra redundancy & storage of raidz2 for cheaper scalability.
 

Bidule0hm

Server Electronics Sorcerer
Joined
Aug 5, 2013
Messages
3,710
I don't see any problem besides the management of course ;)

NB: a RAID-Z2 of 4 drives is safer than 2 mirrors (same number of drives and same redundancy overhead in both case) so you might want to add the drives 4 by 4 in RAID-Z2 vdevs instead of 2 by 2 in mirrors vdevs.
 

ShimadaRiku

Contributor
Joined
Aug 28, 2015
Messages
104
Good point. I'll have to consider spending more upfront on a 4x4TB raidz2 config.
 

DrKK

FreeNAS Generalissimo
Joined
Oct 15, 2013
Messages
3,630
4x4TB as RAID-Z2 will have somewhat worse performance, I believe, than a pair of mirrors. But I agree, also, that in most cases, a man with a 4 drive pool willing to take on 2 drives of redundancy is most often best served by RAID-Z2.
 

Bidule0hm

Server Electronics Sorcerer
Joined
Aug 5, 2013
Messages
3,710
Excepted it's not a pair but two separate mirrors, each one in his own pool.
 

DrKK

FreeNAS Generalissimo
Joined
Oct 15, 2013
Messages
3,630
You know, I need to read these posts more carefully instead of just blasting through them at night before bed. Thanks Bidule. :)
 
Status
Not open for further replies.
Top