Netbackup Communication Buffer configuration - NET_BUFFER_SZ

[Robert_H_Abed]

Hi,
I need to optimize the speed of the backup on all the clients in my infratructure.
I have set the communication buffer on all windows servers to 256K and created NET_BUFFER_SZ in UNIX servers to 262144.

I need to know what is the highest (best) value I can set? can I set it to 1MB?512K?etc..?
how can I calculate the best value for the Communication Buffer for any client?
how can I optimize the backup speed?

thanks,
Robert

[Srikanth_Gubbal · Accepted solution]

Symantec guides always rocks...

http://seer.entsupport.symantec.com/docs/183702.htm
http://seer.entsupport.symantec.com/docs/307083.htm

[Robert_H_Abed]

Thanks. I will check the documentation provided.

[Taqadus_Rehman]

 http://seer.entsupport.symantec.com/docs/244652.htm

[Robert_H_Abed]

thanks Taqadus,
I actually set the communication buffer to 256K on Windows, the NET_BUFFER_SZ to 262144 on Linux. and on both media and master NUMBER_DATA_BUFFERS 64 and SIZE_DATA_BUFFERS 65536
there's a huge improvements on unix but on Windows it is is slow, like 6 or 7 Mbps as a throughput.
on Linux it is between 15 and 30 Mbps.

All the LAN s Gigabit Ethernet, and the tape library is ML6020 LTO3/ Master and Media servers on Win 2k3 SP2 Netbackup 6MP6.

Any additional settings on the client/server/media server can be done to increase the backup speed?

thanks for your input

[Taqadus_Rehman]

• Please tell me what is the actual size of (windows) backup?
• Is this backup contain many small files? if yes then Run the following bpbkar throughput test on the client with Windows:

C:\Veritas\Netbackup\bin\bpbkar32 -nocont > NUL 2>
 

(for example, C:\Veritas\Netbackup\bin\bpbkar32 -nocont c:\ > NUL 2> temp.f)

• Do you please check TCP/IP throughput?

• Disk I/O can also effect the backup throughput do check that as well. 

 

[Robert_H_Abed]

Hi

The actual size varies from one server to a server; it is around 20GB (a couple goes up to 50) for more than 20 servers.
I have tried the the command, it retuns a blank line.
Network utilization on the backp interface is quite normal.10 to 20 % during the backup in 1 GB Network interface
Disk read is max reaching 16400000Bytes / sec.
Yes some servers have a lot of small files to backup.

Once some servers, I have increasing hte communication buffer to 512KB, I had an improvement in the performance, not what expected.



Thanks Again Taqadus.

[CY]

Hi Robert,

You need to create the bpbkar log directory on the Widnows client to do the test Taqadus told you.

C:\Program Files\VERITAS\NetBackup\logs\bpbkar

After you run the bpbkar32 -nocont test on the Windows client (wait for a while even thouth it seems doing nothing), go to the bpbkar log directory and you whoudl see a log created, such as 040909.log.  Open it with WordPad (or make a copy and open it if it says the file is accessed by another application), and you should see something like this:

12:00:22.810 PM: [7580.7588] <2> tar_base::backup_finish: TAR - backup:       elapsed time:        654 secs    127416036 bps

which tells you how fast NetBackup client (bpbkar process) can read on that local Windoows machine.  In the case above is 127416036 byte/sec = 121 MB/sec.  I can never run backup that fast from this Windows machine, so as the Symantec document (see below) suggested, you should run at least 3 times on the dataset with > 10 GB size to get a clear figure.

(DOCUMENTATION: How to benchmark the performance of the bpbkar32 process on a Windows client )
http://seer.entsupport.symantec.com/docs/242918.htm

[Taqadus_Rehman]

 Netbackup take longer to backup multiple small files of the same total size as a single large file. what you can do is

- use FlashBackup (or Flashbackup-Window) policy type. this is feature of netbackup advance client (if you have advance clients).

- Make sure  Netbackup process are free from Viruse Scan. this may double performance.

- Make sure the NetBackup buffer size is the same size on both the servers 
and clients.

- Turn off NetBackup Client Job Tracker if the client is a system server.. 

- Regularly review the patch announcements for every server OS. Install patches that affect TCP/IP functions, such as correcting out-of-sequence delivery of packets.