netbackup buffers and Solaris restrictions
1) What good is a high NET_BUFFER_SZ (262144) when tcp_recv_hiwat and tcp_xmit_hiwat are set to low values (49152 or 48 Kb). Solaris kernal has the default at 49152. Symantec in the following tech note states NET_BUFFER_SZ is no good unless those 2 values are also set to a higher value.
(FYI I have SIZE_DATA_BUFF = 131072 and NUMBER_DATA_BUFF=128 and tcp_time_wait_interval=1000)
I dont have an issue changing them on my Master n Media servers, but the catch is that Symantec recommends the NET_BUFFER_SZ to be the same on Media and Client servers to improve the performance. Most of my client servers are Oracle DB or Apps servers and OS is perf tuned for those apps. The DB Admin are not sure if increasing tcp_recv_hiwat and tcp_xmit_hiwat also increase the memory utilization. (RMAN itself puts them on the edge given the load it takes along with the nightly batch jobs)
I need an expert opinion about setting tcp_recv/xmit_hiwat to be the same as NET_BUFFER_SZ although i am trying this out on 6 clients to see the perf change.
2) Symantec in its performance tuning guide 6.5 page 98, says default SIZE_DATA_BUFF for tape is 64 Kb and advises to change it based on the tape drive specs. We have HP LTO-4 and LTO-5 whose spec's state that BUFFER SIZE is 64 MB and 256 MB (not KB). To what extent can we increase these values?