I also noticed you're running RHEL 6.x which runs on the truly ancient
(but pretty reliable) 2.6.32 kernel. The newer 3.11 and 3.13 kernels
are MUCH faster at IO and a lot smarter about caching and when to swap
etc. I've seen several big machines go from a few thousand tps to 15
to 20k tps just from going from 3.2 to 3.13. Keep us updated on
whether or not a pooler works for you.