Network backup and restore performance on AIX can be dramatically slowed with certain NetBackup/AIX configurations.

Problem

Network backup and restore performance on AIX can be dramatically slowed with certain NetBackup/AIX configurations.

Error Message

N/A

Cause

This can occur when the NetBackup network buffer size is mismatched to the AIX tcp_sendspace and tcp_rcvspace settings.

Optimum performance was realized when the NetBackup network buffer size (configured with the /usr/openv/netbackup/NET_BUFFER_SZ file) is adjusted to equal the size set in the network options for AIX.

Performance degradation was seen when the NET_BUFFER_SZ file was set to 65536 and the following settings were configured within AIX:

no -o rfc1323=1
no -o sb_max=1310720
no -o tcp_sendspace=262144
no -o tcp_recvspace=262144
no -o udp_sendspace=65536
no -o udp_recvspace=655360
chdev -l en0 -a state=up -a rfc1323=1 -a tcp_recvspace=262144 -a
tcp_sendspace=262144

Troubleshooting: Examine the host and NetBackup configuration as detailed above.

Log Files: N/A

Solution

Changing the contents of the NET_BUFFER_SZ file from 65536 to 262144 resolved the performance issues.

Note: It is usually best to allow the operating system manage TCP memory usage by placing a zero (0) into the NET_BUFFER_SZ file. NET_BUFFER_SZ should only be used if the O/S defaults are low and cannot be increased. See Related Articles below (100016112).

For additional information on performance tuning, one would previously refer to the NetBackup™ Backup Planning and Performance Tuning Guide, however please note that content is related to media servers in which AIX is no longer supported as a media server. See Related Articles below (100041478)