Upgrading NAS with 8 disks in main pool, best practice for vdevs?

mrgerry123 · May 8

Hi guys, just bought a new case with room for 10 3.5 inch drives and was planning to expand to an 8 disk raidz main array for media which will be read heavy and write light and a 2 disk mirrored array which will have a lot of small files and be heavier in the write department (for stuff like computer backups and documents, steam games etc).

For the 8 disk array is it better practice to run two 4 drive raidz1 vdevs or one 8 drive raidz2 vdev? All of the 10 drives are 10tb drives with the mirrored ones being sas and the rest being sata. Throughput speed is not a huge concern for the raidz array and I am more interested in reliability. Obviously the raidz2 allows any 2 drive failures but the rebuild process if a drive fails may be longer (OS is truenas scale).

Electronics Wizardy · May 9

I'd probably go z2 if performance isn't a big issue. Rebuilds aren't that much longer.

I'd also be tempted to just make it one big array. The writes on the big array are likely going to be fast enough anyways. I'd argue that the hdds are gonna be to slow for many games these days anyways.

mrgerry123 · May 9

Thanks, to be clear it would simply be for offloading games from my ssd then moving them back to play them. I wouldn't run directly from the nas. When you say one big array you mean a 10 drive raidz2 array?

LIGISTX · May 9

15 hours ago, mrgerry123 said:

Thanks, to be clear it would simply be for offloading games from my ssd then moving them back to play them. I wouldn't run directly from the nas. When you say one big array you mean a 10 drive raidz2 array?

I would also just go with one large array. No reason not to… less loss to redundancy this way.

You can EASILY write or read from a Z2 array at over gigabit networking speeds. There is no point is setting up multiple vdevs for this type of workload. Just use all 10 drives in a Z2 array, or if you want an extra amount of redundancy, Z3, but Z2 should be fine.