[ Thanks to Amy Newman for this link.
]
“Collectl has an interactive mode, playback mode, record mode,
socket mode and plot mode. Interactive is pretty self-explanatory.
The record mode saves to a file for use later — and you can use
the playback mode to replay the data. The plot format saves data in
a delimiter separated format that can be used with plotting
utilities so you can graph system performance data. Finally, the
socket mode directs collectl to send its data to a port specified
with the -A option.“Why would you want to use collectl instead of sar? For one
thing, collectl is supposed to have very low overhead. The author
claims it’s been measured to use less than 0.1 percent when run as
a daemon — although this may not hold for systems with massive
numbers of disks and running processes.”