snlatency(8) snlatency(8)
NAME
snlatency - Measure Xsan Volume network latency
SYNOPSIS
snlatency pathname [repeat]
DESCRIPTION
The snlatency program allows measuring the round trip latency from the
Xsan client to the FSM process on the MDC host. The file system to
measure is selected via the pathname parameter.
snlatency uses a special RPC to the MDC in a loop to measure the time
to send the message, the time for the FSM process to service the re-
quest, and the time to send the response back up to the system call
level. The average of repeat calls is averaged and the latencies
printed out in micro seconds.
If the MDC is not local, then the NTP clock algorithm is used to adjust
for the difference between the two host's clocks before calculating the
results, it is not used when the MDC the same host. The reason for
this is that the NTP algorithm assumes the latency in both directions
is the same and in effect averages them out. Comparing the latencies
seen between the client local to the MDC and remote clients will show
how much of the latency is caused by network infrastrucure.
EXIT VALUES
snlatecy will return 0 on success and non-zero on failure.
Xsan File System June 2014 snlatency(8)
Mac OS X 10.12.3 - Generated Fri Feb 10 08:38:18 CST 2017