For performance, as mentioned, you can use TPC (Tivoli Productivity Center) for disk. You will need to license the software, based on the TB in your DS8000. From there, you start a "performance monitoring" process that will poke the DS8000 each x mins for performance Data...
If you want to only perf your AIX host for example, you could try something along the lines of IOZONE, IOMETER or even Bonnie that will allow you to "benchmark" your filesystem directly on you host. Personnally, i like IOZONE...but there are others...