On Nov 13, 2008, at 1:45 PM, Chris Kirby wrote: > Oh, right, on pools with version >= SPA_VERSION_REFRESERVATION > we add a refreservation for zvols instead of a regular reservation. > > So a 100G zvol will have a 100G refreservation set at creation > time.
Just to clarify this a bit, the reason why we do this is so that snapshots don't steal space from the zvol. One consequence of this is, in order to take a snapshot of a zvol (or any dataset with a refreservation), there must be enough free space in the pool to accommodate the possibility that every block (bounded by the size of the refreservation) that is not already part of a snapshot (the "referenced" or "REFER" bytes) might become dirty. -Chris _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
