If, as the author claims, this one process was chewing up resources by doing a lot of random i/o, the right tool to fix the situation is really ionice(1). ionice(1) modifies the i/o priority of a process in the same way that nice(1) modifies the CPU priority. It's such a handy tool -- I'm always amazed more people don't know about it.
Unfortunately, ionice is not avail on FreeBSD.
Naive use of nice can kill performance. If you have any sort of shared resource on your system, you're begging for a priority inversion. Much more useful is the Solaris Fair Share Scheduler.
Gotcha. The machine is for one purpose only. And it is running on FreeBSD, not Solaris. I was careful to try to not be so naive about the values.
I've seen people renice one of Oracle's many processes then wonder WTF happened when every Oracle process is then waiting for that one to release a lock. Oops :-)
I'd like to see some numbers showing how much of a difference in overall system performance was attained due to the changes he made.
The system is largely idle, so there aren't any great #s on overall system performance. The key is when some background process runs, e.g. a backup, it now runs at lower priority. So when you try to do other stuff during that backup, the other (more important stuff) completes faster.