try dumping to a null device instead of tape to test raw speed without tape.
pick one of your dumps, and then do something like: dump 0f null /vol/vol0
You can see how long the dump takes and compare it to tape.
How many simultaneous dumps do you do? are the tapes on FC or SCSI or over the net? how fast is the path to tape?
if it is over the net, did you check for any errors, like using netstat -a?
On 12/18/06, Ammar Zolkipli ammar.zolkipli.lists@gmail.com wrote:
Gents,
Let me first explain the overall layout. I've got a D2D2T design. Both primary and secondary filers are v-series, and snapvaulted. We have 16TB of CIFS home dir data volumes backing up to tape via NDMP. And the tape backup is on LTO-3 running at sustained throughput of 20mbps, (F**king slow, I know).
Does anybody have experience how to speed up NDMP backup? At this point, the LTO-3 is shoe-shining as the minimum sustained throughput on that drive is 40mbps. And also, does anybody have any experience with NDMP to tell us why this is happening?
Thanks