Complete PC Back is generally unusable to me

Discussion in 'Windows Vista Performance' started by PJ Nelson, Mar 7, 2007.

  1. PJ Nelson

    PJ Nelson Guest

    I this day and age why would you restrict the image file to write only to DVD
    and and NTFS FS? Why? There really is no answer. Unless you have a
    writeable DVD and 30 blank DVDs and/or an drive that you partitioned to NTFS.
    Then I bet your not even asking the question. But on top of that, no
    compression? Really no compression? No incrementals?

    In an effort to make it easy, it is not even close to being usable.
    PJ Nelson, Mar 7, 2007
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  2. Why would you want to write an image file that is going to be larger than 4
    gig to a file system that has a 4 gig limitation (fat32)?



    Richard Urban MVP
    Microsoft Windows Shell/User
    Richard Urban, Mar 8, 2007
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  3. You didn't mention what type of media you want to back up to if not DVD or
    NTFS volumes. There are reasons behind why we require NTFS or DVD and there
    are also differences in the way they are treated:

    --If the target is an NTFS volume, you can do incrementals. The differences
    are stored as shadow copies within the shadow copy storage area on the
    volume. The Volume ShadowCopy Service (VSS) is at the heart of these
    incrementals, and VSS requires NTFS.

    --If the target is an NTFS volume, you cannot compress the .vhd. This has to
    do with the way in which the VSS service works--basically on the incremental
    backup, any compression would lead to huge differences between the current
    vhd and the one on the shadow copy and we will be deleting old shadow copies
    at much higher rate. So the backup algorithm is highly optimized to cause as
    little as possible copy-on-write to be able to keep more backups on the
    target disk. (See blurb below for additional details on copy-oon-write.)

    --If the target is DVD, then we do compress the .vhd but you can't do
    incrementals because of the NTFS requirement for VSS.

    Of course, none of this is obvious from the tool itself, but I wanted to let
    you know that there are technical reasons behind the requirements.

    Additional copy-on-write info I mentioned earlier.
    "Copy-on-write" is Volume ShadowCopy (VSS) terminology. Complete PC Backup
    uses shadow copies to store the incremental changes to .vhd file. These
    updates are stored in a hidden area on your hard disk. This area is
    configurable and can only hold so many shadow copies. Once the area fills,
    oldest shadow copies are purged. The more changes on the volume, the more
    quickly those older shadow copies will be purged. From what the developer
    explained, the act of compressing a .vhd causes it to change more from
    version to version. We want to avoid having those older shadow copies
    purged, so we don't compress the .vhd on hard disks.

    You can find explanations of "copy-on-write" in the Technical Reference at
    Some internet searching also turns up good hits.

    Here's a link to our blog for more info on shadow copies:
    Jill Zoeller [MSFT], Mar 8, 2007
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