On Thu, Jun 29, 2006 at 09:25:21AM +1000, Nathan Kroenert wrote: > On Thu, 2006-06-29 at 03:40, Nicolas Williams wrote: > > But Joe makes a good point about RAID-Z and iSCSI. > > > > It'd be nice if RAID HW could assist RAID-Z, and it wouldn't take much > > to do that: parity computation on write, checksum verification on read > > and, if the checksum verification fails, combinarotial reconstruction on > > read. The ZFS system (iSCSI client) would still have to verify the > > checksum on read... > > > > ...but leaving parity computation/reconstruction to the iSCSI server > > would greatly cut down the amount of I/O needed for RAID-Z to something > > similar to that needed for HW RAID-5. > > But - This still fails to address the design concept of ZFS's end to end > checksumming, and fails to address things gong bad over the system's > hardware bus, the IO card and the Fibre...
No it doesn't. As I'd have it (and as I wrote) ZFS would compute the checksum both, on reads and writes, but on reads the iSCSI target would also compute the checksum, so it could do combinatorial reconstruction if a block is bad. Nico -- _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
