Writing halted on iSCSI zpool

[mav@]

Would that scenario still be able to recreate the data if the first two disks (with the actual blocks) were removed? If not, then it wouldn't qualify as raidz2.

Yes. That is just like 4-disk RAIDZ2. Two parity disks should be enough to recover information if any two data disks missing. Computation price will be high, but better then data loss.