> > Our Netapp does double-parity RAID. In fact, the filesystem design is > > remarkably similar to that of ZFS. Wouldn't that also detect the > > error? I suppose it depends if the `wrong sector without notice' > > error is repeated each time. Or is it random? > > On most (all?) other systems the parity only comes into effect when a > drive fails. When all the drives are reporting "OK" most (all?) RAID > systems don't use the parity data at all. ZFS is the first (only?) > system that actively checks the data returned from disk, regardless > of whether the drives are reporting they're okay or not. > > I'm sure I'll be corrected if I'm wrong. :)
Netapp/OnTAP does do read verification, but it does it outside the raid-4/raid-dp protection (just like ZFS does it outside the raidz protction). So it's correct that the parity data is not read at all in either OnTAP or ZFS, but both attempt to do verification of the data on all reads. See also: http://blogs.sun.com/bonwick/entry/zfs_end_to_end_data for a few more specifics on it and the differences from the ZFS data check. -- Darren Dunham [EMAIL PROTECTED] Senior Technical Consultant TAOS http://www.taos.com/ Got some Dr Pepper? San Francisco, CA bay area < This line left intentionally blank to confuse you. > _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
