3 drives in raidz 250GB and 2 x 2TB = 453.7 GiB?

[Nolan]

Hi,

i'm totally new to freenas and stumbling round at the moment, i've set up a volume with the 3 drives i've got one of which is a 250GB and 2 x 2TB's.
How has it worked out that volume from the 3 disks? is the 250GB drive imparing the other two or have i missed something completely?

Thanks,

Nolan

 

[jgreco]

It's taken 250GB from each drive. One drive's worth of space is burned for parity. You have 500GB of usable space. Since the 250GB drive is probably sized in marketingspeak, it's probably more like 225GB, so you really have 450GB of space.

It all works out. In a RAID set, you really need same-sized drives. And if you don't provide that, most RAID implementations will happily "assist" you by MAKING them all the same size.

 

[Nolan]

Ah so I was over zealous in putting all 3 drives into 1 volume. For now I'd be best just using the 2tbs as one volume? Cheers
I thought there was something I was missing based on the 250gb.

 

[jgreco]

Yeah, the 250GB is not that useful. Basically with RAIDZ, if you lose one drive, you can still access your data, right? But you only get 500GB that way (3 x 250GB minus one parity). If you just mirror the two 2GB's, you are still able to tolerate the loss of one drive, but you get 2TB that way, PLUS you can use the 250GB as a scratch drive (nonredundant). So that's the better configuration option for you, unless you can get some more 2TB'ers or something like that.