> > You just have to add a stripe at a time rather than > a > > single disk at a time. > > > > Adam > > What does it mean to "add a stripe"? Does that mean > I can add one disk or do I have to add two disks?
I expect he means adding another raid-z vdev to the zpool, i.e. more than one disk. Obviously, if your main goal is to be maximally cheap, that's not ideal. And to my mind, a zpool consisting of multiple raid-z's is less than ideal too, because two drive's worth of parity would be better used spread across the whole pool than each isolated to part of it. You could add a single drive as a vdev unto itself, but that would have no redundancy compared with the rest of the zpool, and either having no redundancy on a zpool (which if the non-redundant device fails would presently cause a panic, I think), or having vdevs at different levels of redundancy within a zpool, aren't at all a good idea. Of course it could be done offline with a backup, destroy and re-create the pool larger, and restore. But that would require something big enough to write the backup to. Doing it online strikes me as quite tricky to say the least (two different stripe sizes while growing, among other things). Apparently some other volume management implementations can do it, from what people have been saying. But it would take one of the gurus to say whether there is anything about zfs that would make it more difficult. -- This messages posted from opensolaris.org
