On Tue, 22 Dec 2009, James Risner wrote:
I do "consider RAID5 as 'Stripeset with an interleaved Parity'", so I don't agree with the strong objection in this thread by many about the use of RAID5 to describe what raidz does. I don't think many particularly care about the nuanced differences between hardware card RAID5 and raidz, other than knowing they would rather have raidz over RAID5.
One of the "nuanced differences" is that raidz supports more data recovery mechanisms than RAID5 does since it redundantly stores its metadata and provides the option to redundantly store user data as well, in addition to what is provided by "RAID5". The COW mechanism also provides some measure of protection since if the corrupted data was recently written, a somewhat older version may still be available by rolling back a transaction group. Valid older data may also be available in a snapshot.
It is not uncommon to see postings from people who report that their single-disk pool said that some data corruption was encountered, the problem was automatically corrected, and user data was not impacted.
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
