On a VMware 5.5 ESXi host I suddenly experienced guest machined that hanged or froze. I had to reset the guest machine to get it up and running again. In the Events tab I could see entries like below at the time of freezing.
Lost access to volume 51d15c1a-17706da4-0ae6-001f29e5c998 (datastore1) due to connectivity issues. Recovery attempt is in progress and outcome will be reported shortly.
Device mpx.vmhba1:C0:T0:L0 performance has deteriorated. I/O latency increased from average value of 69864 microseconds to 4383213 microseconds.
I started to check my disks and raid as I suspected a failing disk, but the disks and raid was in working order.
It turned out that the problem started around the time I did a guest snapshot. The datastore had about 14 GB free space out of it’s 924 GB capacity and this seems to be to0 little. After deleting a couple of snapshots the problem disappeared.
When the snapshots had been deleted, I also had to consolidate some of the virtual machines disks.