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.
I'm running a CentOS 6.6 with Kernel 2.6.32-504.el6
Is it possible to upgrade to the 3.13 version using Centos 6.6? (I think only in Centos 7)
Is so, can you please provide me any link that shows a IO improvement between two kernels? something that I can study