Extending ZFS Questions

[ss4johnny]

I'm reading through the docs about extending a ZFS volume and I had a few questions. If I have a RAIDZ2 and extend it with another RAIDZ2 (at least four disks), then each group of disks (the original and the new) has sort of a separate redundancy. So I can have up to two disks fail in the first group and up to two disks fail in the second group. Is this correct?

So if instead of using four disks to extend a RAIDZ2 with another RAIDZ2, then if I just use one and extend it as a stripe, then this stripe will not be able to tolerate any failures. Correct?

 

[SweetAndLow]

1. yes
2. yes and to clarify if the striped vdev has a failure you will lose the whole pool. The more overarching theme here is if you lose full redundancy on any vdev you will lose the pool.

 

[ss4johnny]

I didn't put it together on the second point. That is pretty terrifying. Thanks.