On Tue, Aug 18, 2009 at 04:22:19PM -0400, Paul Kraus wrote: > We have a system with some large datasets (3.3 TB and about 35 > million files) and conventional backups take a long time (using > Netbackup 6.5 a FULL takes between two and three days, differential > incrementals, even with very few files changing, take between 15 and > 20 hours). We already use snapshots for day to day restores, but we > need the 'real' backups for DR.
zfs send will be very fast for "differential incrementals ... with very few files changing" since zfs send is a block-level diff based on the differences between the selected snapshots. Where a traditional backup tool would have to traverse the entire filesystem (modulo pruning based on ctime/mtime), zfs send simply traverses a list of changed blocks that's kept up by ZFS as you make changes in the first place. For a *full* backup zfs send and traditional backup tools will have similar results as both will be I/O bound and both will have more or less the same number of I/Os to do. Caveat: zfs send formats are not guraranteed to be backwards compatible, therefore zfs send is not suitable for long-term backups. Nico -- _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
