I need to produce some comparative filesystem performance metrics for our virtual hosting environment. Specifically, I need to look at the difference between NFS and iSCSI and at the performance impact of changing the network MTU from 1500 to 9000. This is my first foray into filesystem performance metrics...there's a tremendous amount of information out there (and so many tools!) and I'm not sure exactly where to start.
Complicating things are the fact that these systems each have 48 cores and 256 GB of memory, and I'm not sure exactly how this might impact the setup of my performance measurement tools. For example, the iozone documentation recommends setting the maximum file size to be larger than the local memory of the system...but this suggests a maximum file size of at least 512GB.
I'm hoping someone can provide some suggestions (or a pointer to some documentation) for (a) setting up some reasonable tests, and (b) interpreting the results.