optimal Buffer Size/Number settings for VTL in NBU 7.1

[Edwin_Danso]

Is there a recommended Buffer Size/Number settings for VTL for NBU Server v7.1 for SuSE?

(For instance, for OST its is 256K/64)

Thanks,

Edwin Danso

edwintdanso@hotmail.com

[mph999 · Accepted solution]

It depends - there are tuning settings and so what works for one environment, may not work for another.

However, a size setting of 262144 is a good starting point.

Regarding number, try 128, run test, note the speed then try 256 and see if it improves.

Martin

[Edwin_Danso]

(the environment is EMC Data Domain DD670, Data Domain OS 5.1.1.0)

[Marianne]

Ask your EMC reseller for their Best Practice docs. I remember some years ago at a customer where EMC EDLs were used as VTL, the EMC guys gave us a doc with NBU tuning recommendations. Please bear in mind that buffer settings for VTL will also be used for physical tape drives.

[Yasuhisa_Ishika]

I prefer to use default buffer size because higher value sometime lead to I/O failure(depending on hardware). Today I have tested on Oracle M3000 server with HP Ultrium 5 drive. I got 150MB/s with default buffer size and 64 buffers, and 330MB/s with 128 buffers.