ESX, ESXi, and Virtual Machine Logs
Logs can help you find out what happened if commands do not have the desired results. On ESXi 5.0 systems, find all logs in the /var/log directory. Some of the items in that directory are symbolic links from the /var/run/log directory.
On ESXi 4.1 systems, you can find the following logs.
After you reboot your machine, files /root/vmkernel-log.<date> and /root/vmkernel-core.<date> are present.
vmware.log in the same directory as the VMX file for the virtual machine
<virtual_machine_name>/<virtual_machine_name>.vmx located on a datastore associated with the managed host. Use the virtual machine summary page in the vSphere Client to determine the datastore on which this file is located.