Network buffer size
I am seeing some performance issue:
Client name is server1, OS: win 2003, NBU: 7.0.1
Media server=Client is server1; (media server is backing up itself)
Master NBU: 7.0.1, OS win2008 r2
Backup is going to Quantum disk DXi4520
NIC on media has 2GB throughput and Quantum has 4 NICs bonded together, so max is 2GB;
Backup throughput is 19-30MB, sometimes 40MB, but not exceeding.
Found in the log that buffer is waiting to be empty, so client is sending data faster than media server is writing to disk. Buffer values are 32 and 256K.
Question is, i found in the bptm log this:
io_set_recvbuf: setting receive network buffer to 1049600 bytes;
1. What does this mean?
2. Does this impact the perfromance?
3. Is it possible to tune it? If yes what value max?
4. if yes Does the change make impact for other things?
Hope for your help and answers as always.
Thanks!
Quantum have a NetBackup best practices guide for the DXi - worth asking them for a copy - i have a NBU 6.5 version but most things should apply.
One extract:
NET_BUFFER_SZ
Note the NET_BUFFER_SZ value is the size of the buffer on the media server that receives data from the client server.
To change the Net_Buffer_SZ:
1. Create the NET_BUFFER_SZ file in the <INSTALL_PATH>\NetBackup directory.
Note: The file name is case sensitive and must have no extension. The value in the file needs to
be a multiple of 1024. If the file is not present, the default value of 262144 (or 256K) is used.
2. Add the appropriate value to this file.
Our lab testing has yielded improved performance by matching the Buffer_Size on the clients to
NET_BUFFER_SZ on the media server.
Buffer_size
Please note the value of the Buffer_size does not show up in the bptm log file, but can be viewed and set
from the master server or by modifying a registry value.
The default value for the Buffer_size setting is 32K.
Changing the client server, the buffer size (Buffer_size) can be modified from the application user interface.
Changing the Client Buffer_size (called communications buffer):
From the NetBackup Administration console, Host Properties | Clients, double-click the client you
are configuring.
Expand the options under Windows Client | select Client Settings. Change the Communications
buffer to the desired size in KB.Network-Attached Storage Settings and Tuning
If you experience slow performance on disk storage units and disk staging storage units, implement the
following recommendations:
1. Increase the data buffers used by Symantec NetBackup disk manager process on the master and
media servers. The Default value is set to 262144 (256K)
2. Create a file <install path>/usr/openv/netbackup/db/config/SIZE_DATA_BUFFERS_DISK
Add the value 1048576 to the file content. Note: The file name is case sensitive
3. Create a file <install path>/netbackup/db/config/NUMBER_DATA_BUFFERS_DISK
Add the value of 16 to the file. This can be increased based on available memoryHope this helps
