[Veritas-bu] buffer level settings for STK 9940b drives

Remember that's ~25MB of shared memory for one job to one tape drive,
and more if you are multiplexing.

(num_data_buffers *
size_data_buffers)*num_of_tape_drives*max_MPX_setting 

The above calculation is for how much shared memory is required by
NetBackup.  If you exceed this you will start getting backup errors.
Refer to the NetBackup Troubleshooting Guide (Status Codes) under Status
Code 11 for more detail.



David A. Chapa | ADIC | 720.272.8452 cell | http://www.adic.com
Sr. Technical Advisor


-----Original Message-----
From: veritas-bu-admin AT mailman.eng.auburn DOT edu
[mailto:veritas-bu-admin AT mailman.eng.auburn DOT edu] On Behalf Of
ida3248b AT post.cybercity DOT dk
Sent: Friday, August 13, 2004 1:52 PM
To: Schaefer, Harry; veritas-bu AT mailman.eng.auburn DOT edu
Cc: veritas-bu-admin AT mailman.eng.auburn DOT edu
Subject: Re: [Veritas-bu] buffer level settings for STK 9940b drives

Hello Harry

What I would try was

NUMBER_DATA_BUFFERS = 96
SIZE_DATA_BUFFERS = 262144

NET_BUFFER_SZ = 262144 

as the STK9940B is 30 MB/s native and the STK9840A which the technote
was 
made for is 10 MB/s. But these settings requires that you media server
have 
enough shared memory configured in /etc/system

What I usally do is make the above configuration and then decreases 
NUMBER_DATA_BUFFERS until I stop getting status 89

Regards
Michael


On Thu, 12 Aug 2004 17:02:19 -0400, Schaefer, Harry wrote
> Does anyone else use STK 9940B drives? We had previously tuned our 
> buffers to match what Technote #236103 said regarding how to tune 
> STK 9840 drives, which is:
> 
> NUMBER_DATA_BUFFERS = 32
> SIZE_DATA_BUFFERS = 262144
> 
> Thing is, I am seeing nothing regarding full buffers, but craploads 
> of "waited for empty buffer" messages. We only have two 9940 drives 
> per media server (Sun v240) and they run inline tape copy, so it is 
> a solid stream of data coming across a gig link to essentially one 
> drive that is rated to do 30 mb/sec native, 40+ mb compressed.
> 
> Just wondering if anyone is doing anything similar and what they are 
> doing as far as buffer settings. The frustrating thing is my logs 
> are telling me that I do not have enough buffers, but I cannot find 
> any guidance (Veritas manuals, technotes, etc.) regarding how high 
> to bump them up to...
> 
> Harry S.
> Atlanta
> 
> -----Original Message-----
> From: veritas-bu-admin AT mailman.eng.auburn DOT edu [mailto:veritas-bu-
> admin AT mailman.eng.auburn DOT edu] On Behalf Of Mark.Donaldson AT cexp DOT 
> com 
> Sent: Tuesday, August 10, 2004 6:00 PM To: veritas-
bu AT mailman.eng.auburn DOT edu
> Subject: [Veritas-bu] Monitoring perfomance at the buffer level
> 
> Here's a quick and dirty script that sweeps the bptm logs on a media 
> server for a supplied policy name and reports the "fill_buffer,
>  waiting on empty buffer" and "write_backup, waiting on full buffer" 
> statistics.
> 
> Output looks like this:
> 
> >policy_perf Hot_PRD
> ## Gathering data..........Done.
> ## Write to buffer waiting on available buffer:
> Min: 0  Avg: 356  Max: 5877 with 285 samples
> 
> ## Write to tape waiting on full buffer:
> Min: 0  Avg: 43373  Max: 290583 with 7 samples
> 
> The "Hot_PRD" is the name of my policy (no safety checking on this 
> one - type it right or get back nothing).  It then sweeps *today's* 
> bptm logfile and counts up the times that the process writing to the 
> tape buffers was waiting on an empty buffer to become available and 
> it also counts up the times that the process writing to the tape was 
> waiting for a buffer to become full before it could write the data 
> to a tape.
> 
> If the Write to Buffer is waiting for an available empty buffer a 
> whole bunch, then perhaps you should increase your buffer count.  If 
> you're tape writing process waiting on a full buffer a lot, then 
> you're starving your tape drives and you should find a way to 
> increase the delivery of client data to your media server or 
> increase your multiplexing factor.
> 
> More info available here:
> http://seer.support.veritas.com/docs/244652.htm (NT but applicable 
> to unix)
> 
> ...and here...
> http://seer.support.veritas.com/docs/183702.htm
> 
> Here's the script.  Watch for line-wrap issues if you cat and paste, 
> it wraps pretty badly and e-mailing through Exchange often adds more 
> wrapped lines...
> 
> Have fun with it.
> 
> -M
> 
> > cat policy_perf
> #!/bin/ksh
> 
> policy=$1
> 
> today=`date +%m%d%y`
> TMPFILEf=/tmp/`basename $0`.tmp.f
> TMPFILEw=/tmp/`basename $0`.tmp.w
> 
> [ -f $TMPFILEf ] && rm -f $TMPFILEf
> [ -f $TMPFILEw ] && rm -f $TMPFILEw
> 
> echo "## Gathering data.\c"
> for pid in `grep  "START BACKUP.*-cl $policy"
> /usr/openv/netbackup/logs/bptm/log.$today |\
>   awk '{print $2}' | sort -u | tr -dc "[0-9]\012" ` do
>   echo ".\c"
>   awk '$0~/\['$pid'\]/ && $0~/fill_buffer.*waited.*empty/ {print
$13+$16}'
> /usr/openv/netbackup/logs/bptm/log.$today >> $TMPFILEf
>   awk '$0~/\['$pid'\]/ && $0~/write_backup.*waited.*full/ {print
$9+$12}'
> /usr/openv/netbackup/logs/bptm/log.$today  >> $TMPFILEw done echo
"Done."
> 
> echo "## Write to buffer waiting on available buffer:"
> awk '{if (NR==1){min=$1;max=$1;sum=$1;count=1} else
>                 {if($1<min){min=$1}
>                  if($1>max){max=$1}
>                  sum=sum+$1 ; count++}}
>       END {if (count>0){print "Min:", min," Avg:",int(sum/count+.5),"
> Max:",max, "with",count,"samples" } 
>            else {print "No Data Found."}}' $TMPFILEf [ -f $TMPFILEf 
> ] && rm -f $TMPFILEf
> 
> echo "\n## Write to tape waiting on full buffer:"
> awk '{if (NR==1){min=$1;max=$1;sum=$1;count=1} else
>                 {if($1<min){min=$1}
>                  if($1>max){max=$1}
>                  sum=sum+$1 ; count++}}
>       END {if (count>0){print "Min:", min," Avg:",int(sum/count+.5),"
> Max:",max, "with",count,"samples"} 
>            else {print "No Data Found."}}' $TMPFILEw [ -f $TMPFILEw 
> ] && rm -f $TMPFILEw
> 
> exit
> 
> -M
> 
> =================================================
>   (2B|^2B) == ?
> =================================================
>   Mark Donaldson - SA - Corporate Express 
=================================================
> _______________________________________________
> Veritas-bu maillist  -  Veritas-bu AT mailman.eng.auburn DOT edu 
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_______________________________________________
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