First FreeNAS Build

[King_Silas]

Hi folks,
Been wanting to get serious about my storage solution for a while now and finally getting around to doing it.
I'm going to be using parts that i have lying around generally, i5 650, ASUS P55 MB, probably 16GB RAM.
Just wondering on my hard drives. I currently have 2x 2TB and 2x 3TB, I've read that its best to have odd numbers of drives for ZFS, so I was planning on getting another 3TB. Would with be the best solution?

I'm guessing I'd have about 6TBs of space correct? With the option when needed to replace the 2TB drives with 3TBs when needed?

 

[jgreco]

The rule isn't "odd number of drives for ZFS." It is more along the line of "power of two plus parity", so for RAIDZ1, 3 or 5 works out well, for RAIDZ2, 4, 6, or 10 works out well, and for RAIDZ3, 7 or 11 works out well. It is not a requirement, just what works out best internally as a result of the way ZFS works.

If you did RAIDZ1 with a 2x 2TB and 3x 3TB in a vdev, that fits the rule. Since ZFS would only be able to make use of the first 2TB of each drive, and that's four drives worth of space plus parity, that gets you about 8TB (actual somewhat less of course due to various reasons). Many users here would be uncomfortable with that layout, though. If you lose one drive, you become reliant on all the other drives working flawlessly in order to rebuild the failed drive. RAIDZ2 is favored for that reason.

 

[King_Silas]

Ahh I see. Thanks for that. I think I will go for the mix of drives for the moment - then when i upgrade the 2TBs to 3TBs, I can use the 2TBs plus a couple extra to make another VDev.
Just need to get my new house wired up then I'll be ready to proceed :)