Creating ZFS software RAID volume with two different size disks

[ajbrehm]

I have an 8 TB and a 10 TB hard drive. Can I create a ZFS software RAID volume on those two?

If yes, can I extend it later from almost 8 to almost 10 TB when In replace the 8 TB drive with a second 10 TB drive?

 

[sretalla]

I have an 8 TB and a 10 TB hard drive. Can I create a ZFS software RAID volume on those two?

Yes, although with only 2 disks, you will either be creating a stripe with no redundancy or a mirror, so I'll discuss the case for mirror here as no redundancy isn't good.

The result will be the same as a mirror of 2 8TB disks. (8TB of capacity)

If yes, can I extend it later from almost 8 to almost 10 TB when In replace the 8 TB drive with a second 10 TB drive?

If you replace the 8TB disk with a 10TB one (now a mirror of 2 10TB disks), you will then have a pool of 10TB capacity (assuming you didn't turn of the auto-expand setting which is on by default).

 

[ajbrehm]

Beautiful! That's good. I just ordered my second HPE server for use with TrueNAS.

 

[ajbrehm]

Turns out it doesn't work, creating a pool with two differently-sized disks. TrueNAS informs me that

"Mixing disks of different sizes in a vdev is not allowed. "

Update: It appears to be possible to "force" it. All good.

 

[sretalla]

Update: It appears to be possible to "force" it. All good.

Yes, I forgot to mention that part... you can ignore the "recommendation".

 

[ajbrehm]

It's all good. the 8 TB pool is there and working. Thanks!