2-5 times a day I get a warning in the events log that looks like this...
Device naa.600508b1001c2be40929c423819e3359 performance has
deteriorated. I/O latency increased from average value of 5627
microseconds to 235837 microseconds.
warning
It's always the same device. This is running on an HP ML350 G6 and a RAID 1 configuration. 20GB RAM. Three VM guests.
I am using the ESXi 5.1 bits downloaded from HP.
We have replaced the System board, Drive Backplane and the connecting cable. The next option is to start replacing the hard drives.
Is there a configuration change I should be making.
I'm very new to this technology, so be kind 
Thanks