Thank you for your reply, let me tell you the full story
1. i noticed that one of my ESX hosts was disconnected from VC, it was pingable but disconnected. the vm's on the host were down.
2. i believe HA did not kick in because the host did not completely go down.
3. the vmmessage file stated that a manual cutover was initiated from hba 1 to hba 2. I don't see any red lights on my hba so i don't think the HBA i bad.