Note: These notes are for ESX server, not confirmed for GSX...

There are four options you can use to change virtual machine logging and log
rotation behaviors:
	logging
	log.rotateSize
	log.keepOld
	log.fileName


logging
Logging ON or OFF:
	logging="false"
	logging="true"

log.rotateSize
By default, the virtual machine log file (vmware.log) is rotated as a result
of the virtual machine's Power On or Power Off operation. To configure log
rotation based on file size, include the following option in the .vmx file of
the virtual machine:
	log.rotateSize=

The following example specifies the vmware.log file to be rotated when its
size reaches 100 kilobytes:
	log.rotateSize=100000

log.keepOld
By default, ESX Server 3.0 keeps six rotations of the vmware.log file
(vmware.log, vmware-1.log, vmware-2.log...). To change the level of rotation,
use the log.keepOld option. The following example specifies the level of
rotation to be 10:
	log.keepOld=10

log.fileName
To specify an alternative location or filename for virtual machine logging,
use the log.fileName option. The following example specifies "myVMlog" as the
new file for logs instead of the default "vmware.log":
	log.fileName="myVMlog"

The next example directs logs to be written to an alternate directory called
"myVM" in a different VMFS volume, "vol1":
	log.fileName="/vmfs/volumes/vol1/myVM/myVM.log"