On Mon, Feb 02, 2009 at 08:22:13AM -0600, Gary Mills wrote: > On Sun, Feb 01, 2009 at 11:44:14PM -0500, Jim Dunham wrote: > > I wrote: > > > > >I realize that this configuration is not supported. > > > > The configuration is supported, but not in the manner mentioned below. > > > > If there are two (or more) instances of ZFS in the end-to-end data > > path, each instance is responsible for its own redundancy and error > > recovery. There is no in-band communication between one instance of > > ZFS and another instances of ZFS located elsewhere in the same end-to- > > end data path. > > I must have been unclear when I stated my question. The > configuration, with ZFS on both systems, redundancy only on the > file server, and end-to-end error detection and correction, does > not exist. What additions to ZFS are required to make this work?
This is a variant of the HW RAID thread that recurs every so often. When redundancy happens below ZFS then ZFS cannot provide end-to-end error correction other than by using ditto blocks. But people using HW RAID typically don't want to dedicate even more space to redundancy by using ditto blocks for data. You still get end-to-end error detection, of course. ZFS layered atop ZFS across iSCSI, with the lower layer providing redundancy, exhibits the same result. You get end-to-end error detection, but not end-to-end error correction. Nico -- _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
