Multiple pools of mirror vdevs

[ShimadaRiku]

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]

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]

Good point. I'll have to consider spending more upfront on a 4x4TB raidz2 config.

 

[DrKK]

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]

Excepted it's not a pair but two separate mirrors, each one in his own pool.

 

[DrKK]

You know, I need to read these posts more carefully instead of just blasting through them at night before bed. Thanks Bidule. :)