VDEV design recommendation

[Nvious1]

I am working on a new freenas build and in this build I will have 24 x 512 GB SSDs and also 24 x 480 GB SSDs. These are repurposed from an old all flash array from work. I want it to be a RaidZ2 Pool and I am not sure how to best group my drives into vdevs. Please let me know your recommendations.

 

[Chris Moore]

I would suggest eight drives in each vdev. Total of six vdevs. Theoretically, you will have a bottleneck at the drive controller. Generally speaking, twelve SSDs is enough to fully saturate the PCIe bus link to the controller card.

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[DrKK]

So, there's a terminology problem here. "I want it to be a RAID-Z2 pool". Pools are not RAID-Z2. Only vdev's are.

Are you saying, you want your pool to consist entirely of RAID-Z2 vdevs? If so, what Chris is suggesting is fine. But, I am forced to ask, on what basis have you determined that you will be using RAID-Z2 vdevs? With so many drives, why are RAID-Z3 vdevs a possibility for you?

 

[Nvious1]

Thanks Chris for the recommendation.

@DrKK sorry for the terminology mix up. Reason for going with RaidZ2 is planning on using it mostly for backup / file share type store and would like to have the happy medium of disk failure tolerance and maximizing the size. Yeah I do have alot of disks but their sizes are small. If they were all 2 TB disks I would go Z3 for sure.