On Jan 31, 2010, at 9:39 AM, Bob Friesenhahn wrote: > On Sun, 31 Jan 2010, Tony MacDoodle wrote: > >> Has anyone encountered any file corruption when snapping ZFS file systems? >> How does ZFS handle open files when compared to other file system types that >> use similar technology ie. Veritas, etc...?? > > I see that Richard did not really answer your question.
Yes, there are many cases where applications can get out of sync, as Bob mentions. But from the file system perspective, ZFS snapshots are safe. > > Zfs snapshot captures the exact state of data which is already committed to > disk. Zfs may buffer written data up to 30 seconds before committing it to > disk. Synchronous writes go to disk essentially immediately, and before > returning control back to the application. Also, when you take a snapshot, the txgs will be committed prior to the snap. -- richard > > Since written data may be in an inconsistent state, it is certainly quite > possible for a snapshot to contain "corrupted" data from the perspective of > the application, similar to the way that data may be corrupted after a system > panic or power failure. An application which knows about the snapshot > mechanism can synchronise its data to disk before requesting a snapshot. > > Bob > -- > Bob Friesenhahn > bfrie...@simple.dallas.tx.us, http://www.simplesystems.org/users/bfriesen/ > GraphicsMagick Maintainer, http://www.GraphicsMagick.org/ > _______________________________________________ > zfs-discuss mailing list > zfs-discuss@opensolaris.org > http://mail.opensolaris.org/mailman/listinfo/zfs-discuss _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
