How would I find out how many IOPS my Linux system can handle?
Generally you will want to use a benchmark utility like fio. When measuring the amount of IOPs keep in mind that you need to think about things such as:
These will all effect the amount of IOPs you get. You want to make sure that with these tests you consider the response time it takes to fulfill these requests in the results.
Also remember when performing these tests you want to make sure that you flush the file cache (Howto here: deleting linux cached ram) before each test and that your test file is larger than any controller/disk caches.