ZFS - SSD storage setup?

[chrisb81]

Hi all,

I have a machine with a 4x 2.5" hotswap bay. I also have four 500gb SSD drives. The machine also has a 500gb NvME M.2 drive on board.

I keep changing my mind about the best way to set this up. I had the idea I would great 2x mirrors on the four drives, giving me just under 1TB of usable space, with at least some redundancy and hopefully decent performance.

But then, if I set up 5 drives I could set up RAIDZ2 (I think?), but then I'd have to use the 500gb M.2 drive, which wouldn't exactly be particularly hot-swappable.

The machine also has 6 3.5" hot-swap bays, so my idea was to use the 3.5" bays for a great deal of storage, then the 2.5" bays for VMs that could use the performance.

I'm sorry if this is a pretty basic question, I've been reading up on ZFS for what seems like weeks and I just can't figure out what the best solution would be. I've been testing a 2x mirror using the 4 SSDs and that seems pretty good, but then I just don't know what to do with the M.2 on board.

Any ideas, thoughts would be greatly appreciated.

Thanks,

Chris.

 

[aaron]

If you want VMs to access it, only use ZFS mirror vdevs (can be multiple in a pool -> RAID 10 like). Using any RAIDz for VM disks will not give you the best performance regarding IO operations / seconds (IOPS) and will usually surprise you with an unexpected high space usage. More details can be found in the docs.

Overall, mirrored drives all the way. I use single drives only for things where I really don't care if I lose them.

 

[chrisb81]

If you want VMs to access it, only use ZFS mirror vdevs (can be multiple in a pool -> RAID 10 like). Using any RAIDz for VM disks will not give you the best performance regarding IO operations / seconds (IOPS) and will usually surprise you with an unexpected high space usage. More details can be found in the docs.

Overall, mirrored drives all the way. I use single drives only for things where I really don't care if I lose them.

Thanks! It sounds like I'm along the right lines with my SSDs then - I set them up as 2 mirrors in a pool so I have ~1TB storage space. I was a bit unsure due to the idea that if I lost two drives in the same mirror, I'd be in trouble, but in reality I should have backups and alerts when a drive goes down, so the main point is to get the best possible performance with some level of resilience.

Thanks for the links to the docs as well, I didn't realise the performance difference with using mirrors vs. RAIDz was so clear cut. I think I might use mirrors with my six 3.5" bays as well.