This is correct, it needs to be set to '1'. From the best practices guide for Networker with DataDomain:
"
When parallelism is applied to a tape or tape-emulating device like a VTL, parallelism often means multiplexing. Multiplexing interleaves backup streams, writing a little of save set 1, then a little of save set 2, and so on, so that none of the clients sending save sets need to wait for the other clients to finish. Unfortunately, this interleaving of save sets has a significant impact on deduplication efficiency when the DDR is used as a virtual tape library (VTL). Multiplexed streams hinder the deduplication process from efficiently identifying blocks of common data because of the additional header information added to the data with parallelism. In order to realize the full benefit of deduplication, EMC recommends multiplexing be turned off when using the DDR as a VTL with NetWorker by setting both target sessions and max sessions on each virtual tape drive to a value of 1.
Not the parallelism of backup server, but rather of tape drive. If you have VTL or disk device, you may create as many as you want of devices (well, there is certain nsrmmd limit to pay attention to) and tweak it to fit your needs.
coganb
736 Posts
0
March 2nd, 2010 03:00
Hi,
This is correct, it needs to be set to '1'. From the best practices guide for Networker with DataDomain:
"
When parallelism is applied to a tape or tape-emulating device like a VTL, parallelism often means multiplexing. Multiplexing interleaves backup streams, writing a little of save set 1, then a little of save set 2, and so on, so that none of the clients sending save sets need to wait for the other clients to finish. Unfortunately, this interleaving of save sets has a significant impact on deduplication efficiency when the DDR is used as a virtual tape library (VTL). Multiplexed streams hinder the deduplication process from efficiently identifying blocks of common data because of the additional header information added to the data with parallelism. In order to realize the full benefit of deduplication, EMC recommends multiplexing be turned off when using the DDR as a VTL with NetWorker by setting both target sessions and max sessions on each virtual tape drive to a value of 1.
"
You can find the full guide on Powerlink at:
Home > Support > Technical Documentation and Advisories > Software ~ J-O ~ Documentation > NetWorker Family > White Papers
-Bobby
ble1
4 Operator
•
14.4K Posts
0
April 14th, 2010 06:00
Not the parallelism of backup server, but rather of tape drive. If you have VTL or disk device, you may create as many as you want of devices (well, there is certain nsrmmd limit to pay attention to) and tweak it to fit your needs.