Do drives need to be identical?

[Patm]

My only NAS experience is with a QNAP ts-410 and that required all drives to be identical. Under FreeNAS is that still the case? I'm looking at using Raid 5 on a dual core intel system.

P.S. I did search a LOT on this and found no reference to such a requirement so I'd assume they don't have to be identical - but then sometimes things everyone just knows isn't mentioned much.

 

[b1ghen]

Not identical as in brand and model, but the capacity should optimally be the same or very close since the smallest drive will determine the size of your vdev.
And the closest you get to RAID5 using ZFS is a RAIDZ, one drives worth of storage is used for parity data spread over all drives.

 

[Patm]

Great thanks!

So if I tossed in a 250 GB drive with 2TB drives then each drive would be treated as if it were 250 GB?

I have all 2TB drives but they aren't the same manufacturer or model etc.

 

[b1ghen]

So if I tossed in a 250 GB drive with 2TB drives then each drive would be treated as if it were 250 GB?

Yes that is correct.

Many people mix drives from different manufacturers on their FreeNas systems, I personally like to keep my drives the same speed (5400rpm, 7200rpm etc.) at least but it's not really necessary.

 

[Patm]

Thanks, makes sense to me. All the drives should be pretty much the same.

 

[trionic]

If one has a pool with four VDEVs, each consisting of six 4TB disks, can that pool be expanded by adding VDEVs consisting of six 3TB disks?

 

[gpsguy]

If one has a pool with four VDEVs, each consisting of six 4TB disks, can that pool be expanded by adding VDEVs consisting of six 3TB disks?

Yes

 

[trionic]

I had thought so, then this line from the manual created doubt:

you can stripe a new vdev (and its disks) with the same type of existing vdev

 

[gpsguy]

I had thought so, then this line from the manual created doubt:

By "type" it's referring to the type of vdev. For example, if your current 6 disk vdev's are RAIDz2, when you extend your pool with another vdev, you should use RAIDz2 again.

assuming your pool consists of 4 x 6 disk RAIDz2 vdev's, imagine if you extended it with a single disk. Instead of being able to lose 2 disks in any vdev, should that newly added single disk fail, you would lose your entire volume.

 

[trionic]

Yes, the current pool is 4 x 6 RAIDZ2 VDEVs and will be extended with 2 x 6 RAIDZ2 VDEVs :)