I think these sets of tests are good. There are some others I'd like to see, but they'd only be applicable if the 1231-ML has hardware cache. I can mention what those are if the card does have hardware caching.

The general concept is: "the more RAM the better". However, if you're using RELENG_7, then there's not much point (speaking solely about ZFS) to getting more than maybe 3 or 4GB; you're still limited to a 2GB kmap maximum.

Regarding size of the array vs. memory usage: as long as you tune kmem and ZFS ARC, you shouldn't have much trouble. There have been some key people reporting lately that they run very large ZFS arrays without issue, with proper tuning.

Also, just a reminder: do not pick a value of 2048M for kmem_size or kmem_size_max; the machine won't boot/work. You shouldn't go above something like 1536M, although some have tuned slightly above that with success. (You need to remember that there is more to kernel memory allocation than just this, so you don't want to exhaust it all assigning it to kmap. Hope that makes sense...)

Only on CURRENT; 7.x cannot, and AFAIK, will never be able to, as the engineering efforts required to fix it are too great.

I look forward to seeing your numbers. Someone here might be able to compile them into some graphs and other whatnots to make things easier for future readers.

Thanks for doing all of this!