Some RAID systems compare checksums on reads, though this is usually only for RAID-4 configurations (e.g. DataDirect) because of the performance hit otherwise.
End-to-end checksums are not yet common. The SCSI committee recently ratified T10 DIF, which allows either an operating system or application to supply checksums and have them stored and retrieved with data. Oracle has been working to add support for this to Linux, and several array and drive vendors have committed to implementing it. So one could say that ZFS is ahead of the curve here. ZFS is not particularly revolutionary: software RAID has been around since the invention of the term; end-to-end checksums to disk have been used since the 1960s (though more often in databases, tape, and optical media); WAFL-like file structures may pre-date NetApp. It does put these together for the first time in a widely available system, though, which is certainly innovative and useful. It will be more useful when it has a more complete disaster recovery model than 'restore from backup.' -- This message posted from opensolaris.org _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
