I see man i/o waits on exflutca6 at the test time:

Tasks: 118 total,   2 running, 116 sleeping,   0 stopped,   0 zombie
Cpu0  :  0.0%us,  0.3%sy,  0.0%ni, 25.7%id, 74.0%wa,  0.0%hi,  0.0%si,  0.0%st
Cpu1  :  0.7%us,  0.3%sy,  0.0%ni, 99.0%id,  0.0%wa,  0.0%hi,  0.0%si,  0.0%st
Cpu2  :  0.0%us,  0.7%sy,  0.0%ni, 99.3%id,  0.0%wa,  0.0%hi,  0.0%si,  0.0%st
Cpu3  :  0.3%us,  0.0%sy,  0.0%ni, 99.7%id,  0.0%wa,  0.0%hi,  0.0%si,  0.0%st
Mem:   3970748k total,  3761900k used,   208848k free,   177372k buffers
Swap:  4114428k total,        0k used,  4114428k free,  3046240k cached
 

I changed the nice value from (ganglia) gmond + gmeta from "0" to "-10" and stoped the irqbalancer.