NBU5.1MP6 running very slow when 4 drives concurrently running

[orafup]

 Hi,

 I have NBU5.1 MP6 backup server with 4 lto3 tape drives. It runs as slow as 2000-5000k/sec each drive speed when 4 drives running simultaneously but when it runs single drive it seems to be fast it could reach up to 30000-35000k/sec . is there anyway that i can maximize the performance?

Thanks,
Jonathan 

[Will_Restore]

Review the Media Manager Device Configuration Guide
http://seer.entsupport.symantec.com/docs/268089.htm

and search the Knowledgbase for 5.1 Tuning
http://www.symantec.com/business/support/overview.jsp?pid=15143

[Marianne]

Hardware specs of your server?
I have a WhitePaper that I've downloaded from HP a couple of years ago. The document is called "Optimizing the performance of HP LTO Ultrium 3"
and lists the following hardware requirement for EACH LTO3 tape drive:
"To drive an HP LTO ULTRIUM 3 in a SAN-based backup environment requires 2-GHz processing power and 1.00-GB RAM and any processing power required for other operations should be built in on top of this requirement."

(I have done a search, but this document seems to be no longer available)

[Mike_Gavrilov]

It isn't possible to give you right solution right now with present information about your environment. You have to perfore some invesigation, check your buffer's size and amount, understand your bottlenecks and so on so on.

[orafup]

It is window 2003 SP2(32bits) and the Library is  STK L80 + 4 HP LTO3 drives and they are all SCSI connected--the adaptec dual ports HBA 160M ; first port connects to the library then rounding back to the first LTO3 drive , the second port cascaded the last 3 drives if i run single policy on any drive it was fast 35M/sec but it is slow if there 4 drives running simultanously.  I have setup bptm on the server and bppkar on client and i have increased the buffers but it even getting slower when the tuning files added. 
By the way, I know Veritas recommend to use Veritas' driver it gives me an error "failed to install at xxxxx008 " when i was trying to install it . it is running on the HP drivers for LTO-3 now.

thanks,
Jonathan

[Andy_Welburn · Accepted solution]

such that there are 2 tape drives per SCSI port? Not sure if it will make much difference as they are all going thru' the same HBA at the end of the day but....


The following is taken from George WInters NetBackup Software Performance Tuning Whitepaper:

"...
As a rule of thumb, it is not advisable to saturate a tape drive connection. There should be no more than two drives per SCSI/FC bus. Also, bear in mind that the host bus adapter (HBA) is an integral part of the hardware connection. If an HBA devide is rated at 100MB/sec, then assume an optimal loading of 70 MB/sec using the 70 percent rule.
..."

So, when you have 4 drives active, what is the overall throughput?