zvols are block storage
datasets are filesystems
Yeah he got the names wrong. In any case, don’t use RAIDZ with zvols . You might get away with an NVMe pool and RAIDZ, but HDD pool + RAIDZ + block storage is a recipe for disaster on performance. Better get your RAM and tunables on their A-game before doing that.
You should. If you have 8 empty bays. zpool replace only removes the old disk from the pool once the process is completed. So no data is missing from the pool no matter how many disks you issue. Might be sub-optimal performance though, never did that myself.
I assume the thread starter didn’t use replace but rather expand. And that’s a totally different process, but people often do talk about replace while they’re actually using zpool expand.