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I am trying to configure a VMware VM to have a non-persistent disk. This is as simple as making the disk independent f the VM, and selecting the non-persisent option. How do I do this in VMWare fusion?

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2 Answers 2

For some reason VMware Fusion 5 (Even VMware Fusion 5 Professional) lacks a UI option to create Independent, Persistent VMDKs. But it can easily be done in the .vmx file using a text editor:

VMware documentation about changing disk mode says that the disk must not have any snapshots, so you may need to delete all snapshots. Consider making a backup first

  1. Shut down your virtual machine and quit VMware Fusion. (Yes, this is necessary)
  2. Locate the Virtual Machine's package in the Finder. Right click on it and select "Show Package Contents"
  3. Locate the .vmx file and open it with a text editor (you can right click and select "Open with > Text Edit")
  4. Search through until you find the line containing name of the virtual disk (vmdk) which you want to make persistent. It should look something like:

    scsi0:1.fileName = "Virtual Disk-000001.vmdk"
    

    (Though it might be ide0:0, or the bus numbers might be different)

  5. Add below that line the following:

    scsi0:1.mode = "independent-nonpersistent"
    

    Make sure to match the bus description. So if your device is ide0:0 you'd write ide0:0.mode

  6. Save the file and relaunch VMware Fusion, you should be good to go.
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For someone new to VMWare and to this non-persistent option - how does this work exactly? Will it emulate the read & write of the hard-drive only in RAM or in some temporary "scratch" folder on a physical disk? –  bigp Jun 8 at 15:08
    
@bigp: yes. Independent disks are not affected by snapshots. Non-persistent disks revert to the state they were in prior to VM start, each time a machine is powered off. They are useful if you want to get a disk set up a certain way for testing, because every time you power off the sandbox gets reset. –  Josh Jun 8 at 15:16
    
From vmware.com/support/ws3/doc/ws32_disks2.html: Changes to disks in nonpersistent mode are not saved to the disks, but are lost when the virtual machine is powered off or reset. Nonpersistent mode is convenient for people who always want to start with a virtual machine in the same state. Example uses include providing known environments for software test and technical support users as well as doing demonstrations of software. Any disk type can be used in nonpersistent mode –  Josh Jun 8 at 15:17
    
Thanks for the clarification @Josh. If I'm running Windows in the virtual machine, and do a "restart" from it, will that flush out the changes, or only if I actually close the VM entirely and relaunch it? –  bigp Jun 8 at 15:28
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If I recall correctly a restart from within the OS will not reset the drive, only powering off or using the VMware "Reset" option (hard reboot) –  Josh Jun 8 at 15:30

It seems you may be over thinking this. Why not just boot the live .iso version of your OS?

I can't say if that's what you want to do particularly since whatever OS you want to use may not be a "live" version. But if you don't "install" to a virtual hard drive then there's almost never any worry about any persistence.

I do it all the time in Virtual Box. I may have to specify a virtual hard drive like a VHD file when installing the machine but that doesn't mean I actually have to install to that drive. In fact, I just delete the virtual hard drive in the machine settings so there's no choice but to boot whatever .iso image I specify. End result, a fully functional virtual OS with absolutely no persistence.

Then again, if we're talking about something like Puppy Linux then even an .iso image might get modified. That's one of Puppies advantages - it's ability to save persistence info to the very disk it booted from.

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