First, how does something like native TAR compare to bpbkar client
process- 

TEST CLIENT NETWORK SPEED TO Master or Media Server   
Requires Rsh to be enabled temporarily if it has been disabled in the
environment

With TAR- 
tar cvf - /(datapath) | rsh (server_name) dd of=/dev/null 
(time this test) 

With BPBKAR
/usr/openv/netbackup/bin/bpbkar -dt 0 -r 888 -nocont /(datapath) | rsh
(server_name) dd of=/dev/null

Additional buffer details- 
TCP/IP Network Buffer Size.
/usr/openv/netbackup/NET_BUFFER_SZ is a file containing a number
indicating the TCP/IP socket buffer size that should be used for data
transfers between the NetBackup media server and its clients. If the
file does not exist, the default value used is 32032 bytes.
The default value can be changed by creating the file
/usr/openv/netbackup/NET_BUFFER_SZ on the NetBackup media server and
client systems.
The /usr/openv/netbackup/NET_BUFFER_SZ file is a text file containing a
single line specifying the value of the Network Buffer Size in bytes in
decimal format.
For example, a Network Buffer Size of 64KB could be configured and
checked like this:
# echo "65536" > /usr/openv/netbackup/NET_BUFFER_SZ
# cat /usr/openv/netbackup/NET_BUFFER_SZ
65536
# 
Specifying a larger value in the NET_BUFFER_SZ file may improve the
performance of backups and restores. It is recommended that if
NET_BUFFER_SZ is used, the same value should be set on all the NetBackup
media servers and clients.
Data Buffer Size & Number of Data Buffers.
The NetBackup media server uses shared memory to buffer data between the
network and the tape drive (or between the disk and the tape drive if
the NetBackup media server and client are the same system). By default,
NetBackup uses a default value of 8 x 32KB shared memory buffers (or 12
x 64KB buffers if multiplexing is being used).
These buffers can be configured by creating the files
/usr/openv/netbackup/db/config/SIZE_DATA_BUFFERS and
/usr/openv/netbackup/db/config/NUMBER_DATA_BUFFERS on the NetBackup
media server. These parameters are meant exclusively for media servers,
and should not be used on a pure master server or client.
The SIZE_DATA_BUFFERS file should contain a single line specifying the
data buffer size in bytes in decimal format.
The NUMBER_DATA_BUFFERS file should contain a single line specifying the
number of data buffers in decimal format.
The value in the SIZE_DATA_BUFFERS file has to be a multiple of 32KB.
It is common to increase SIZE_DATA_BUFFERS to 256KB and
NUMBER_DATA_BUFFERS to 16.
IMPORTANT: Because the data buffer size equals the tape I/O size, the
value specified in SIZE_DATA_BUFFERS must not exceed the maximum tape
I/O size supported by the tape drive or operating system. This is
usually 256K or 128K bytes.
In order to configure NetBackup to use 16 x 256KB data buffers, specify
262144 (256 x 1024) in SIZE_DATA_BUFFERS and 16 in NUMBER_DATA_BUFFERS:
# echo "262144" > /usr/openv/netbackup/db/config/SIZE_DATA_BUFFERS
# echo "16" > /usr/openv/netbackup/db/config/NUMBER_DATA_BUFFERS
# cat /usr/openv/netbackup/db/config/SIZE_DATA_BUFFERS
262144
# cat /usr/openv/netbackup/db/config/NUMBER_DATA_BUFFERS
16
# 
Care should be taken when changing these values. For example, increasing
the tape buffer size can cause some backups to run slower and there have
been cases where there have been restore problems.
IMPORTANT: After making any changes, it is vitally important to verify
that the following tests can be completed successfully:
1. Run a backup.
2. Restore data from the new backup created in step 1.
3. Restore data from a backup created prior to the changes to
SIZE_DATA_BUFFERS and NUMBER_DATA_BUFFERS.
The number and size of the data buffers used by the NetBackup media
server can be checked by looking in the "bptm" log file: 
12:02:55 [28551] <2> io_init: using 32768 data buffer size
12:02:55 [28551] <2> io_init: CINDEX 0, sched bytes for monitoring =
2000
12:02:55 [28551] <2> io_init: using 8 data buffers
or
15:26:01 [21544] <2> mpx_setup_restore_shm: using 12 data buffers,
buffer size is 65536
Increasing the size and number of the data buffers will use up more
shared memory, which is a limited system resource. The total amount of
shared memory used is: (buffer_size * num_buffers) * drives * MPX. So,
for two tape drives, each configured with an MPX of 4, and with 16 data
buffers of 256k, the total shared memory usage would be:
(16 * 256k) * 2 * 4 = 32MBytes (32768 KB)
Take into consideration the total system resources and the entire
network.
The Maximum Transmission Unit (MTU) for the Local Area Network (LAN) may
also have to be changed.
NOTE: For Digital Linear Tape (DLT) drives the number that seems to give
the best performance for SIZE_DATA_BUFFERS is 65536. Further performance
improvements can be achieved by increasing the value in the
NUMBER_DATA_BUFFERS file.
 

 


-----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 Kirsch,
Mathew (Matt)
Sent: Tuesday, December 07, 2004 2:24 PM
To: 'Grover,Samuel'; veritas-bu AT mailman.eng.auburn DOT edu
Subject: RE: [Veritas-bu] Backups running slower for no apparent reason?

That's the doc I used to do the tuning. I've read it six times. It
doesn't
tell you WHAT you should use for settings, or WHY you should use a
particular setting, only HOW to set them...

-----Original Message-----
From: Grover,Samuel [mailto:Samuel.Grover AT cna DOT com]
Sent: Tuesday, December 07, 2004 3:16 PM
To: Kirsch, Mathew (Matt); veritas-bu AT mailman.eng.auburn DOT edu
Subject: RE: [Veritas-bu] Backups running slower for no apparent reason?



http://seer.support.veritas.com/docs/183702.htm

this doc should help:

technote: 183702

-----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 Kirsch,
Mathew (Matt)
Sent: Tuesday, December 07, 2004 1:53 PM
To: veritas-bu AT mailman.eng.auburn DOT edu
Subject: RE: [Veritas-bu] Backups running slower for no apparent reason?


We're trying to maximize performance per the "Veritas Netbackup
Performance
Tuning for Version 3.2/3.4" document. It says we should use a setting of
NUM_DATA_BUFFERS of 32.

What should I be looking for in the bptm log? I have 120MB of raw text
data
to go through, and knowing what to look for would be helpful.

Thanks for the info!

-----Original Message-----
From: David Chapa [mailto:david.chapa AT adic DOT com]
Sent: Tuesday, December 07, 2004 2:14 PM
To: Kirsch, Mathew (Matt); veritas-bu AT mailman.eng.auburn DOT edu
Subject: RE: [Veritas-bu] Backups running slower for no apparent reason?


Was there found to be a compelling reason to change your NUM DATA
BUFFERS?

I'd check the bptm logging to see if there are buffer fill issues.

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

Sr. Technical Advisor

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