Configuring vdevs & pool

[asininedervish]

Hi - I've been unable to figure out how to set up my drives to get the most storage capacity. My goal is capacity, with a degree of redundancy.

Currently: 2 x 4TB, 2 x 8TB drives.

My thoughts were to stripe 2x4TB for an 8TB vdev, and then take all 3x8TB vdevs and set them in Z1, for 16ish TB usable, and any 1 drive failure being withstood. I can't seem to figure out how to do that however.

 

[garm]

What you describe doesn’t work. There is no redundancy across vdevs in ZFS. You lose one you lose the entire pool. Redundancy happens inside the vdevs.

With those drives, your only sane choice is mirrors, that would give you ~ 9.4 TB of usable space.

If you build a RAIDZ1 vdev of the drives you get about the same, but with lower redundancy.

A RAIDZ2 vdev get you ~ 6.3 TB with about the same redundancy as the mirror pairs.

If the data you are going to store is volatile then you can stripe all four drives together, that will give you ~19 TB without redundancy. Lose a drive and you lose the pool.

Wanna play with the numbers?
https://jsfiddle.net/Biduleohm/paq5u7z5/1/embedded/result/

 

[asininedervish]

Yeah, looks like you're right. I presumed there was going to be a way to put vdev's into other vdev's, but doesnt look like it's supported on freenas. I'll just do a RAID10 I guess, despite being inefficient.