Much appreciated for the response Brenton
 
I have performed some tests after analysing bpbkar and bptm logs all all
media servers and a number of their bptm logs indicate that they are not
waiting for empty buffers, in turn telling me that an increase of the
buffer size and number should have a positive impact .
 
 After testing our throughput has jumped around from around 11mb/sec to
40+ mb/sec which is fantastic, my concern is for the latter part of your
mail regarding tapes which have been written with a different 
SIZE_DATA_BUFFERS. 
 
When testing I took backups before and after the SIZE_DATA_BUFFERS
implementation. I then proceeded to test restores from both images
written with different Buffer sizes.
All where successful however could you shed a little more light on this
as we obviously have all our backed up data written in the current
SIZE_DATA_BUFFER and it would be a shame not to achieve the throughput
we saw when testing.
 
 
Thanks in advance
 
Dave

 

________________________________

From: Brenton Carbins [mailto:brenton_carbins at symantec.com] 
Sent: 16 October 2006 01:32
To: Clooney, David
Subject: RE: [Veritas-bu] 9940B


Hi David,
 
 
My clients running 9940B drives are all running a SIZE_DATA_BUFFERS of
262144, with NUMBER_DATA_BUFFERS less important, and dependent on system
resources and kernel settings. I'd suggest 32-64 buffers if you can
achieve this without Error 11s. It is important when you are changing
these settings that you test with maximum anticipated multiplexing and
the maximum anticipated number of drives running, so that resource usage
will hit it's peak, and any problems detected immediately.
 
If you already have lots media written with a different SIZE_DATA_BUFFER
- say 131072, it is probably better not to change this value. If you do
change this value, you will need to re-label existing media before
attempting to write to them again. This may require that you suspend
media until existing images expire.
 
Best of luck,
 
 
 
Brenton
 


________________________________



Brenton Carbins
Senior Systems Engineer
WA and SA Enterprise Products
Symantec Corporation
www.symantec.com <http://www.symantec.com/> 
-----------------------------------------------------
Office: 08 9480 3720
Mobile: 0409 779 230
Fax: 08 9481 3177
Email: Brenton_Carbins at symantec.com
-----------------------------------------------------
 

Compelling New Features
Low Bandwidth, Remote Office Backup
http://www.symantec.com/Products/enterprise?c=newfeatures&refId=1381
 

________________________________

From: veritas-bu-bounces at mailman.eng.auburn.edu
[mailto:veritas-bu-bounces at mailman.eng.auburn.edu] On Behalf Of Clooney,
David
Sent: Friday, 13 October 2006 6:09 PM
To: veritas-bu at mailman.eng.auburn.edu
Subject: [Veritas-bu] 9940B


Hi 
 
Was wondering whether anyone knows the max I/O buffer size for the STK
9940B ?
 
Trying to fine tune some media servers using the SIZE_DATA_BUFFERS and
NUMBER_DATA_BUFFERS.
 
And was thinking the drive would obviously determine what the settings
should be.
 
Regards
 
Dave


________________________________


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