A non-persistent disk will discard all changes when the VM is shut down. This
is good for testing new software or experimenting with settings.
VMware Workstation for Windows and Linux does support non-persistent disks.
While VMware Fusion does not provide the option to create non-persistent disks,
it will support this option.
Either create a VM on Windows or Linux and setup persistent disks, or add the
appropriate line to an existing *.vmx file. The correct line to use depends on
which disk is the boot partition. Typically this will be one of the following:
You can change either to use ide or scsi:
To disable persistence mode, change this line to:
You can confirm this is working by comparing the MD5 sum of the *.vmdk file before and
after running the VM in non-persistent mode.
P/S : Remember! This code only work only if you shutdown/poweroff/reset the OS. If you restart the OS, this code will not work!
credit : http://t0rchthe.net/hacks/VMwareFusionHacks-nonpersistentdisk.txt