SubnetMask
Contributor
- Joined
- Jul 27, 2017
- Messages
- 129
When working with spinning disks, traditionally, but not universally, RAID10 would outperform RAID5/6 (I had a Promise vTrak that according to them was optimized for RAID5, and throughput testing confirmed that RAID5 blew RAID10 out of the water), but on FreeNAS/TrueNAS, RAIDZx provides little to no performance increase, read or otherwise, while stripes or striped mirrors (or mirrored stripes) provide a performance benefit. Now, when talking about spinning disks, when talking about an absolute best of ~200 IOPs, I can certainly see the benefit of a stripe (or mirrored stripe) increasing performance - a 10 disk stripe could bring the IOPs to 2000 IOPs... but what about talking about SSDs that can push 22,000 WRITE IOPs? You'd need a stripe of 110 15K SAS disks to try to equal the write IOPS of that single SSD - that being said, assuming one had a bunch of enterprise grade SAS SSDs that are capable of tens of thousands of write IOPS and hundreds of thousands of read IOPS, What is the drawback to setting up, say, ten of them, in a RAIDZ2 or even Z3 config? I suspect that in many environments, any benefits that could be had setting up ten SSDs in a mirrored stripe vs RAID5/6 would be impossible to really see since each individual SSD is so much faster than any spinning disk. It seems to me that when talking about SSDs, in most cases, 'RAID level' is more about redundancy than performance.