Veritas-bu

[Veritas-bu] NBU Data Buffer sizes

2001-05-07 20:04:55
Subject: [Veritas-bu] NBU Data Buffer sizes
From: MarelP AT AUSTRALIA.Stortek DOT com (Marelas, Peter)
Date: Tue, 8 May 2001 10:04:55 +1000
Tim,

I tend to tune the buffers based on the maximum theoretical throughput
of the tape drive in question.

However to do so you need memory on the server.

You've got it set to 16 and 64512 respectively.

Therefore Netbackup will use 16*64512=1032192 bytes per tape drive
in use.

Assuming the maximum theoretical throughput of a drive is 6MB
I would set SIZE_DATA_BUFFERS to the tape drives optimum block
size (usually 64k, 128k or 256k).

Lets assume its 64k (65536), divide 6291456 bytes (6MB) by 65536 bytes (64k)
you
get 96 NUMBER_DATA_BUFFERS. That should be the optimum setting.

Regards
Peter Marelas

-----Original Message-----
From: Tim Allen [mailto:tallen201 AT hotmail DOT com]
Sent: Tuesday, 8 May 2001 1:06 AM
To: Veritas-bu AT mailman.eng.auburn DOT edu
Subject: [Veritas-bu] NBU Data Buffer sizes


Hello.

A database backup is taking a bit longer than expected, and I was 
considering bumping up the data buffers.
SIZE_DATA_BUFFERS is currently 64512 and NUMBER_DATA_BUFFERS is 16.

The bptm log has the following entries;

04:12:47 [12400] <2> fill_buffer: [12399] socket is closed, waited for empty

buf
fer 462164 times, delayed 466388 times, read 40990432 Kbytes
04:12:47 [12399] <2> write_data: waited for full buffer 1100 times, delayed 
1262
2 times
04:29:51 [12433] <2> fill_buffer: [12432] socket is closed, waited for empty

buf
fer 492546 times, delayed 498792 times, read 43451936 Kbytes
04:29:51 [12432] <2> write_data: waited for full buffer 1206 times, delayed 
1131
1 times
06:52:49 [13024] <2> fill_buffer: [13023] socket is closed, waited for empty

buf
fer 426891 times, delayed 430477 times, read 37139232 Kbytes
06:52:49 [13023] <2> write_data: waited for full buffer 591 times, delayed 
10367
times
07:45:18 [13096] <2> fill_buffer: [13095] socket is closed, waited for empty

buf
fer 543885 times, delayed 549783 times, read 47816800 Kbytes
07:45:18 [13095] <2> write_data: waited for full buffer 930 times, delayed 
5408
times
08:13:28 [13810] <2> fill_buffer: [13808] socket is closed, waited for empty

buf
fer 38963 times, delayed 103462 times, read 2457696 Kbytes
08:13:29 [13808] <2> write_data: waited for full buffer 0 times, delayed 0 
times
08:48:43 [14012] <2> fill_buffer: [14011] socket is closed, waited for empty

buf
fer 38882 times, delayed 103166 times, read 2457696 Kbytes
08:48:44 [14011] <2> write_data: waited for full buffer 0 times, delayed 0 
times
09:23:17 [14150] <2> fill_buffer: [14149] socket is closed, waited for empty

buf
fer 37823 times, delayed 100564 times, read 2386784 Kbytes
09:23:18 [14149] <2> write_data: waited for full buffer 0 times, delayed 0 
times
09:54:18 [14302] <2> fill_buffer: [14301] socket is closed, waited for empty

buf
fer 34057 times, delayed 90351 times, read 2150432 Kbytes
09:54:19 [14301] <2> write_data: waited for full buffer 3 times, delayed 32 
time
s
10:05:10 [13608] <2> fill_buffer: [13607] socket is closed, waited for empty

buf
fer 550854 times, delayed 557508 times, read 46860128 Kbytes
10:05:10 [13607] <2> write_data: waited for full buffer 85 times, delayed 
2284 t
imes
10:18:30 [13885] <2> fill_buffer: [13884] socket is closed, waited for empty

buf
fer 421021 times, delayed 424891 times, read 39006624 Kbytes
10:18:30 [13884] <2> write_data: waited for full buffer 597 times, delayed 
3158


There are more delays waiting for an empty buffer than a full buffer so I 
was considering bumping the SIZE_DATA_BUFFERS to 129024.

Hmmm...  I guess the only reason for sending this e-mail was to ask if this 
sounds reasonable for what is in the bptm logs?

I'll have to try it and find out if this improves anything next time.


Tim Allen


_________________________________________________________________
Get your FREE download of MSN Explorer at http://explorer.msn.com

_______________________________________________
Veritas-bu maillist  -  Veritas-bu AT mailman.eng.auburn DOT edu
http://mailman.eng.auburn.edu/mailman/listinfo/veritas-bu

<Prev in Thread] Current Thread [Next in Thread>