10 disks: RaidZ2 x 2 (5 + 5) or RaidZ3?

[vooze]

So I'm getting 10 disks, instead of my current 8. Since I'm gonna rebuild the array anyway, I might as well get some good ideas.

Currently running RaidZ2, but I value my data, so I'm thinking maybe Raidz2 x 2 or RaidZ3 this time.

All disks are 5 TB.

Looking at https://calomel.org/zfs_raid_speed_capacity.html it seems the performance from Raidz2 x 2 is not very great, compared to RAIDz3.. Is this not the whole story?

I'm virtualizing freenas from 2 x H200 in ESXi, so I can do 10Gbit or more, so performance is important for VMs :)

So what do you think? Is it worth it to "loose 1 disk" to performance?

 

[gpsguy]

If you are looking for performance with your VM's you would be better off by striping 5 mirrors.

 

[sretalla]

2x5 RAIDZ2 = 4 disks lost to parity, can lose at least 2 disks with no data loss (maybe as many as 4 if it's 2 from each of the 5), performance of 2 VDEVS
1x10 RAIDZ3 = 3 disks lost to parity, can lose any 3 disks (no matter which 3), performance of 1 VDEV (perhaps a bit better than 50% of the first option)
5x2 MIRROR = 5 disks lost to parity, can lose only 1 disk (although up to 5 can be lost as long as no 2 are in the same mirror), performance of 5 VDEVS... would be the winner on performance by a considerable margin.

 

[vooze]

I understand 5xmirror would be best performancewise. I'm more looking at 2 x Raidz2 or one raidz3. How much performance gain can I expect?

 

[sretalla]

2 VDEVS could be around twice the performance of a single one, but will depend on the load spreading done by the OS (if you start with the 2 from the beginning, it should be almost doubling a single VDEV performance from the beginning and there should be no reason for it to stop... if you add another VDEV or more later, the performance will not be even across the new and old VDEVS, so it's harder to put a number on the increased performance, if any, in that case).

 

[sretalla]

To really "answer" your question, I would say that if you don't care about the capacity aspect, go for the 2 VDEV option every time... performance rules.