This message was deleted.

Absolutely RAID. Spinning disks won’t give you a fair experience unfortunately.

Install everything onto a single RAID? Or split the OS?

I’d keep the os on a separate disk. RAID the storage separately. Have done similar with lvm stripped mirror.

300GB disk for OS. And create two large RAID disks.

Is there a performance reason vs creating 1 raid? (context is I have 18 hosts that all have 8 drive slots)

You can do one. I guess any failures would be handled by the RAID

Plus we have disk redundancy through longhorn.

2 disks for the OS? 6 for DATA raid disk?

These boxes were a place we were going to offer students VMs with a "run this for free with basically no SLA" And we have so many nodes. that if we lost one it's not a big deal.

If you use the RAID5, you can reduce the replica to 2. That gives almost the same protection ratio as replica 3 w/o RAID. That might give better performance/latency. Also, it is recommended to use a hardware raid card instead of a software raid.