Meaning of SQLIO output "counts per second" I realise that my question isn't strictly 'database' but I know that a lot of DBA's will use the SQLIO tool to check I/O performance on their systems so I'm hoping that somebody here will be able to answer this question:

When I run SQLIO the 3rd line of output says something like:

using system counter for latency timings, 14318180 counts per second

What does that mean?  I get different values on different systems, and because I'm comparing different systems I would like to know what that number is telling me (if anything).
It's an informational message, which can be ignored.

This is just the conversion factor between the timer mechanism the program uses internally and actual, real time. See this for a bit of background.

The per-second metrics that the program outputs are the ones you want to focus on. Have a look at this blog post for a tutorial on how to use SQLIO and interpret its output.