The best course is to actually run dump:
To perform a level 0 dump of volume "vol0" to the NULL device enter:
date; dump 0f null /vol/vol0 ; date
To perform a level 0 dump of volume "vol2" to a remote filer null device:
date; dump 0f remote_filer:null /vol/vol2 ; date
Of course, you might want to redo that and use ssh/rsh to establish the dump remotely so you do not tie up your console. Then you can watch things like sysstat to see how fast it is actually moving.
This is usually the very first thing to do when troubleshooting dump: Is it NDMP or dump? This will rule out NDMP and the tape drive as being your problems. If the dump is slow, then it is likely your filesystem.
--tmac
On 3/27/07, Darren Dunham ddunham@taos.com wrote:
Sometimes when troubleshooting backups I want to see if the host can drive data to a tape drive at high speed without involving a filesystem or backup software or the like.
I've got some slow NDMP backups on some filers that have fiber-attached LTO-3 drives.
At the moment I'm assuming that the contents of the filesystem make it difficult to drive the tapes at high speed, but it would be nice to have another data point that would show that the local drive is or is not behaving properly.
Is there any way to have the filer send data to the drive without actually invoking an NDMP backup or running a 'dump'? On another host I might mount a scratch tape and run 'dd if=/dev/zero of=/dev/tape' with an appropriate block size and count.
I see a 'dd', but I don't know of a data source like /dev/zero. Is this or something similar possible?
Thanks.
-- Darren Dunham ddunham@taos.com Senior Technical Consultant TAOS http://www.taos.com/ Got some Dr Pepper? San Francisco, CA bay area < This line left intentionally blank to confuse you. >