I'm looking at backing up our filer to tape for DR purposes.  I've tested both smtape and dump and was surprised that dump was 3 times faster than smtape.  The test was preformed on a idle filer.  The filer is the destination for SnapMirrors at night and idle during the day.

Given that smtape is a block backup I'd expect it to be as fast or faster than dump.  The test Volume contains a single LUN.

FAS3210> version
NetApp Release 8.0.2P6 7-Mode: Fri Jan 27 14:48:08 PST 2012


- filer is idle

FAS3210> sysstat -u 1
CPU Total Net kB/s Disk kB/s Tape kB/s Cache Cache CP CP Disk
ops/s in out read write read write age hit time ty util
2% 0 1 0 0 0 0 0 2s 100% 0% - 0%
1% 0 2 2 0 0 0 0 2s 100% 0% - 0%

- dump to null takes about 13 minutes

FAS3210> date; dump f null /vol/papayasg1_mirror; date
Tue Oct 16 12:48:06 PDT 2012
DUMP: Using Full Volume Dump

DUMP: Dumping tape file 1 on null
DUMP: Date of this level 0 dump: Tue Oct 16 03:17:08 2012.
DUMP: Date of last level 0 dump: the epoch.
DUMP: Dumping /vol/papayasg1_mirror to null
DUMP: mapping (Pass I)[regular files]
DUMP: mapping (Pass II)[directories]
DUMP: estimated 126361315 KB.
DUMP: dumping (Pass III) [directories]
DUMP: dumping (Pass IV) [regular files]
DUMP: Tue Oct 16 12:53:07 2012 : We have written 52672652 KB.                         50GB@171MB/sec
DUMP: Tue Oct 16 12:58:07 2012 : We have written 99181873 KB.                        44GB@151MB/sec
DUMP: dumping (Pass V) [ACLs]
DUMP: 125867380 KB 120GB@155MB/sec
DUMP: DUMP IS DONE
Tue Oct 16 13:01:18 PDT 2012

- smtape backup to null takes 44 minutes

FAS3210> rdfile /etc/log/backup
(null) Tue Oct 16 13:05:32 PDT /vol/papayasg1_mirror CLI-Backup (null)
19 Tue Oct 16 13:05:32 PDT /
vol/papayasg1_mirror BKP-Start (level 0 backup of Backup Set ID 2bc95ed2-195f-11e2-8766-00a09813e8e0)
19 Tue Oct 16 13:05:32 PDT /vol/papayasg1_mirror BKP-Params (originator=CLI mode=dw-data tape_record_size=240KB tape=null all_snapshots tape_seeding)
19 Tue Oct 16 13:05:33 PDT /vol/papayasg1_mirror BKP-DW-Start
19 Tue Oct 16 13:50:26 PDT /vol/papayasg1_mirror BKP-DW-End (phase completed in 0:44:53; 34394279 blocks moved)
19 Tue Oct 16 13:50:26 PDT /vol/papayasg1_mirror BKP-Tape-Stats (wait_time=0s wait_count=0 total_count=0 avail_count=0/0/0/0)
19 Tue Oct 16 13:50:26 PDT /vol/papayasg1_mirror BKP-End (backed up 137.577 GB bytes in 0:44:54; performance=183.844 GB/hour)


--
Pete Kain
310-506-4475