Monitoring Bandwidth usage for individual hosted sites on osx server?

Question

Does anyone know of a good way to monitor bandwidth consumption for individual websites hosted on osx server?

Answer 1

Part of this answer depends on server configuration details that you haven't provided.
Are you looking for 'bandwidth' as in total bytes transferred for any given site? or are you looking for a megabits-per-second network throughput calculation?
Are your various sites logging to separate log files? or a single, unified log file?
If you want a total bytes transferred calculation, then that data is stored in the standard log files, so a simple parser that adds up the response sizes would suffice - it will tell you that x number of bytes/megabytes were transferred.
A bandwitch utilization graph (e.g. mbps) is a little trickier, though.
Are your sites running on the same port, using name-based virtual hosting to separate the traffic, or are they running on different ports?
If different ports then you may be able to implement some kind of network monitoring, but if they're all running on the same port (e.g. 80) then that doesn't work - you're down to Apache logging.
The standard Apache logs, though, don't include enough data to calculate a bandwidth graph. It does include timestamps of requests, and the total bytes in the reply, but that's not enough - the timestamp is only accurate to the second, and there's no indication of duration... for example, a 1mb web page served in 1 second equates to 8mbps, but that same file transferred in 30 seconds is only about 273kbps.
Since the transfer time is required to calculate the bandwidth utilization for the site, you'll need to amend your logging to include the transfer size. You'll need to enable mod_logio and add the %O (output bytes) and %T (request time) variables to your log format. Only then can you calculate the bits-per-second throughput of your site.