There are two choices to benchmark IO-stack (storage/OS/filesystem) against a given application:

• Install the application
• Install an application simulator

Installing the application can be complicated...for complicated application.
On the other hand, running an application simulator is great, because it's quicker to install and run.
As I wanted to find the best filesystem to run a mail server, I stumbled on this great mailstore simulator
I was able to run numerous test runs, before deploying my application.

other interesting simulator I used:
- filebench
- Netapp Simulator
- vdbench
- iometer
- slamd
- mailstore simulator