On Mar 31, 2010, at 9:22 AM, Edward Ned Harvey wrote: >> Would your users be concerned if there was a possibility that >> after extracting a 50 MB tarball that files are incomplete, whole >> subdirectories are missing, or file permissions are incorrect? > > Correction: "Would your users be concerned if there was a possibility that > after extracting a 50MB tarball *and having a server crash* then files could > be corrupted as described above." > > If you disable the ZIL, the filesystem still stays correct in RAM, and the > only way you lose any data such as you've described, is to have an > ungraceful power down or reboot. > > The advice I would give is: Do zfs autosnapshots frequently (say ... every > 5 minutes, keeping the most recent 2 hours of snaps) and then run with no > ZIL. If you have an ungraceful shutdown or reboot, rollback to the latest > snapshot ... and rollback once more for good measure. As long as you can > afford to risk 5-10 minutes of the most recent work after a crash, then you > can get a 10x performance boost most of the time, and no risk of the > aforementioned data corruption.
This approach does not solve the problem. When you do a snapshot, the txg is committed. If you wish to reduce the exposure to loss of sync data and run with ZIL disabled, then you can change the txg commit interval -- however changing the txg commit interval will not eliminate the possibility of data loss. -- richard ZFS storage and performance consulting at http://www.RichardElling.com ZFS training on deduplication, NexentaStor, and NAS performance Las Vegas, April 29-30, 2010 http://nexenta-vegas.eventbrite.com _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
