Pool Question - Wide Z3 for Backups

[Scharbag]

I am upgrading my production pool. 1 of the 2 6-drive Z2 vDevs will go from 4TB to 6TB drives. This will also free up some 4TB drives that I can move into my backup pool.

My backup pool is a single vDev 12 disk Z2 vDev. It is a mix of 3TB and 4TB drives. I will not have enough 4TB drives to complete the backup pool upgrade. I am considering, once my production pool is resilvered and running stable, is to destroy and re-configure my backup pool (pucker factor while waiting for Rsync...). All this pool is used for is snapshots and Rsync backups. Reads would only be required on a file restore so speed is not a concern for me.

My question is: is it unwise to run a single 18 drive Z3 vDev for backup purposes? My other option, and likely preferred, would be to run 2 9 drive Z2 vDevs, one made up of 4TB and one made up of 3TB drives. Even though it has 4 parity drives, it does not waste 1TB*9 drives... The choices...

I have a 20 bay and a 24 bay chassis, so once I add the new 6TB drives, I will be space limited and will be forced to upgrade in place. Not a big deal as either option will require the replacement of 9 3TB drives before additional space is realized through auto expand. My 3TB drives are the oldest and my plan is to replace them with 4TB drives as they fail.

Anywhoo, which way makes more sense (I think I figured out the answer as I typed this... :) )?

Cheers,

 

[Ericloewe]

My question is: is it unwise to run a single 18 drive Z3 vDev for backup purposes?

Probably. That's a lot of disks for a very low IOPS figure...

My other option, and likely preferred, would be to run 2 9 drive Z2 vDevs

That does sound preferable.

 

[Scharbag]

Probably. That's a lot of disks for a very low IOPS figure...


That does sound preferable.

Yeah, as I finished typing the question I kinda sorta figured it out. My new drives should be here today, so I will first re-arrange my disks, throw the new ones into the system, torture them a little bit and then replace some 4TB drives in the production pool. Once that is all stable, I will see what I want to do regarding the backup pool. Gives me the heebejebees to destroy my backup pool and then have no backups for a couple days while it copies stuff across... Anything irreplaceable is also in the cloud so I am good there, but man it would kill my buzz to lose other data though...

One more question though: Once I am ready to replace 4TB drives with 6TB drives, is it OK to replace multiple disks at the same time?

Cheers,

 

[Ericloewe]

Yes, you can replace as many disks at once as you have free SATA ports.

 

[Scharbag]

Thought that would be the case. Just making sure everything is stable then I will start the process.

Cheers,

 

[Scharbag]

Well, 6TB drives are doing their final long SMART test. Started the tests last Friday in the afternoon. Going to be done testing 5@6TB drives tomorrow. These big drives are getting painful to test!!

Cannot imagine doing this on 10TB or larger disks.

Resilvering will begin tomorrow I hope. Should have a larger pool by Thursday :)