Problems with disk array in ESXi 5.1 U1(performance has improved)

HI all,

I have installed an ESXi 5.1 U1 build 1117900 host in a HP ProLiant ML350 G6 with an integrated SmartArray P410i (configured with 3 local SATA disks as a RAID5). This storage controller has BMC (256 MiB) and BBWC, but I am suffering disk performance problems:

vobd.log:2013-07-03T11:20:29.164Z: [scsiCorrelator] 2599614081952us: [vob.scsi.device.io.latency.improved] Device naa.600508b1001ce3f64766bee699998380 performance has improved. /O latency reduced from 6394 microseconds to 1255 microseconds.

vobd.log:2013-07-03T12:21:44.161Z: [scsiCorrelator] 2603289068119us: [vob.scsi.device.io.latency.improved] Device naa.600508b1001ce3f64766bee699998380 performance has improved. /O latency reduced from 1255 microseconds to 727 microseconds.

I have tried to reconfigure disk resources in the vms, without luck.

Any idea how can I debug this?? Exists some solution?? Or maybe th solution could be to use a second server acting as a NAS??

Many thanks.