On Mon, Dec 15, 2008 at 01:36:46PM -0600, Bob Friesenhahn wrote: > On Mon, 15 Dec 2008, Ross Smith wrote: > > > I'm not sure I follow how that can happen, I thought ZFS writes were > > designed to be atomic? They either commit properly on disk or they > > don't? > > Yes, this is true. One reason why people complain about corrupted ZFS > pools is because they have hardware which writes data in a different > order than what was requested. Some hardware claims to have written > the data but instead it has been secretly cached for later (or perhaps > for never) and data blocks get written in some other order. It seems > that ZFS is capable of working reliably with "cheap" hardware but not > with wrongly designed hardware.
Order of writes matters between transactions, not inside transactions, and at the boundary is a cache flush. Thus what matters really isn't write order as much as whether the devices lie about cache flushes. _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
