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Thread: Virtual PC file size problem?

  1. #1
    Bronze Member Coffee's Avatar
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    Exclamation Virtual PC file size problem?

    Not being using VPC for long now and it's been working fine so far. I've come across a bit of a problem using a 'Dynamic Disk' with it's file size being much larger than it should be. The disk properties when in the guest PC reports as about 2.5g but on the host says 4.3g. It suggests using a disk utility to zero out the useless/deleted data, although none seems to be included with VPC ?


    When using a 'Dynamic Virtual Hard Disk', as you write data to the disk the size naturally increases. However when you delete files from a virtual hard disk, the data associated with these files is usually not removed. Instead, it is 'marked for deletion' and is still available for use by the operating system. data is not actually deleted until it is overwritten. You must run a disk utility program to 'zero out' the deleted data before using the compact option in the 'Virtual Disk Wizard'.
    It's hard to find any 3rd party apps to use for this and most of them take a long time, so i've put together a little script that makes use of a util thats built in to XP.

    Don't worry, it's not a virus!

    Coffee.
    Last edited by Coffee; February 8th, 2004 at 17:49 PM.
    Live long and prosper!

  2. #2
    Junior Member
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    Feb 2004
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    There are also plenty of commercially available, shareware, or freeware programs to 'zero out' the deleted data. I've read that Norton Utilities can, as well as programs like Eraser (first one I tried, it is pretty slow but how often do you do this? Kind of like defragging, it's not a daily thing.) which adds a handy right-click to the Explorer context menu. (http://www.snapfiles.com/get/eraser.html) You will need to add an overwrite type for writing all zeroes, that's what Virtual PC wants rather than a more security-minded random pattern.
    Last edited by sholleran; February 24th, 2004 at 18:32 PM.

  3. #3
    Bronze Member Coffee's Avatar
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    The only trouble with most comercial software that does this is that most of them do 3 processes/jobs, 1) writing 0x00(zeroing out) 2) writing 0xff(filling up free space) 3) writing random numbers. It's most certainly like defragging only takes a lot longer, so i guess you probably wouldn't do it too often and having something like a right click context menu in IE may only get in the way.
    Live long and prosper!

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