On Thu, Dec 18, 2008 at 10:24:26AM +0200, Johan Hartzenberg wrote: > Similarly, adding a device into a raid-Z vdev seems easy to do: All future > writes include that device in the list of devices from which to allocate > blocks.
In general, I agree completely. But in practice there are limitations that folks might not be aware of. With Raid4, you can just add a column, because new data can be written into the column, and the existing parity for the written stripe can be updated. With RaidZ, a single added column isn't very useful on a full (or nearly-full) vdev. Each new block written must have at least one disk and one parity write in the stripe on separate disks. So adding one disk to a full raidz will add very little capacity. I don't know how you'd display that issue to the admin either. -- Darren _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
