On Wed, 30 Dec 2009, Richard Elling wrote:
are written because you also assume that you can later read either side. For ZFS, if only one side of the mirror is written, you know the bad side is bad because of the checksum. The checksum is owned by the parent, which is an important design decision that applies here, too.
In a mirror vdev, each mirror contains a complete copy of the vdev, and the last commited TXG can be used to know if the mirror is up to date with its peers, or if it needs a little bit of resilvering to catch up. This differs from a raidz/raidz2 vdev, where most of the disks (N-1 or N-2) need to be available in order to have a complete copy of the vdev.
Bob -- Bob Friesenhahn bfrie...@simple.dallas.tx.us, http://www.simplesystems.org/users/bfriesen/ GraphicsMagick Maintainer, http://www.GraphicsMagick.org/ _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
