Combining a striped vdev in a raidz1 array?

[io7m]

Hello. I have the following drives:

A: a 2TB HDD
B: a 2TB HDD
C: a 4TB HDD
D: a 4TB HDD

I would like to combine these into a pool such that I get ~8TB of usable storage and two drives have to fail simultaneously to lose the pool. I believe the correct configuration would be to stripe A + B yielding one 4TB vdev, and then create a raidz1 pool consisting of (A + B) + C + D.

Try as I might, I can't seem to work out how to actually describe this configuration to the zpool command. Is this configuration actually possible?

[no-usernames-left]

I recommend you create two mirror vdevs, 2x2TB and 2x4TB, and then you use those two to create a 6TB pool with good resilience and very good performance.

[io7m]

Could you elaborate a bit on why this is better?

The machine will have daily backups, and storage size and read performance is more important than write performance, if it helps.

[io7m]

Additionally, could you confirm if the original arrangement is even possible? It feels like it just isn't, based on the syntax of zpool create alone.

[amotin]

@io7m No, what you are asking is impossible by means of ZFS itself. You may be able to create some other concatenation RAID out of those disks to use that as RAIDZ member, but that is on you and your OS.

[io7m]

OK, thanks!