Backing up from within Windows. Moving target !

Discussion in 'Acronis True Image Product Line' started by Mooly, Jun 26, 2009.

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  1. Mooly

    Mooly Registered Member

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    I use TI 10 running Vista and have always wondered two things.
    First, how can an image be created when the operating system is in use and files are constantly changing.

    And secondly leading on from that, is it OK to use a PC while an image is being made.
    Should add I have never had a problem and use TI to make running incrementals to the D partition on a notebook. Have restored several time's always perfectly, but these two points have always puzzled me.
    Thanks
     
  2. K0LO

    K0LO Registered Member

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    Mooly:

    When you start a backup, TI makes a "point in time" snapshot of the file system. Any activity that starts after this snapshot will not be included in the backup image file. The technology behind this is described on the Acronis web site, and is one of the advantages of TI.

    Yes, you can continue to use the computer while a backup is being made. If you're using the default compression setting on a fairly modern PC, the performance "hit" is not too bad. Just remember that any change that you make after a backup starts will not be included in the backup.
     
  3. bodgy

    bodgy Registered Member

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    There was a post by Acronis a couple of days ago that went into great detail on this.

    Basically TI takes a snapshot of a portion of your drive and puts it memory which is then locked. As it writes this snapshot to the image file it checks to see if that area of drive has altered, if it has it records the alteration and then unlocks the memory and moves on to the next chunk of drive to repeat.
     
  4. Earthling

    Earthling Registered Member

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    I'm sure you aren't the only one who wonders how this bit of magic is performed, but it's done by a service called Volume Shadow Copy which as Bodgy has explained can sync and snapshot the whole caboudle while it's still running.

    In Vista this Volume Shadow Copy service is also used by System Restore to create your restore points, and if you install ShadowExplorer you can actually see, and retrieve if you want, earlier copies of any file, one for each restore point. So if a particular file gets corrupted, here's another way to get out of the mire ;)

    http://www.shadowexplorer.com/
     
  5. K0LO

    K0LO Registered Member

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    Although some of the corporate products may use Microsoft Volume Shadow Copy Service, VSS, to create a backup, the home products do not, AFAIK. Acronis has their own patented technology used in TI Home. Here is a description from Acronis Support.
     
  6. Earthling

    Earthling Registered Member

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    Ooops, sorry about that :oops:

    Anyway, hopefully what I said about the VSS will help someone.
     
  7. Mooly

    Mooly Registered Member

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    Thanks all, that's answered it very well. Will have a read at those links too.
    I must admit to preferring TI every time compared to Windows system restore and it's saved the day more than once. I do use just the default settings (compression etc).
     
  8. Robin A.

    Robin A. Registered Member

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    All imaging programs I know of use similar technologies, some of them developed by Microsoft, others proprietary. TI may have "advantages", but this is not one of them.
     
  9. Acronis Support

    Acronis Support Acronis Support Staff

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    Hello Mooly,

    Thank you for using Acronis True Image 10.0 Home

    As Acronis True Image programs use Snapshot technology there are no restrictions using different applications while performing backup archive creation.

    Here is a description of the unique Acronis Snapshot technology:

    Once Acronis True Image initializes the backup process of a volume (which logically corresponds to a single partition, if there are no Dynamic Disks), Acronis Snapshot Manager flushes the file system mounted to that volume temporarily freezing all the operations on the system volume. Immediately thereafter, the Snapshot Manager driver creates a point-in-time view of the system volume and a bitmap describing the used sectors on this volume. Once the bitmap is created, the filter driver unfreezes the I/O operations on the system volume. It generally takes only several seconds to create a point-in-time view of the volume. After that, the operating system continues working as the imaging process is under way.

    Acronis True Image reads the sectors on the system volume according to the created bitmap. Once a sector is read, the appropriate bit in the bitmap is reset. In its turn, the Acronis driver continues working to hold the point-in-time view of the system volume. Whenever the driver sees a writing operation directed at the system volume, it checks whether these sectors are already backed-up, if they are not, the driver saves the data to the sectors that will be overwritten to a special buffer created by the software, then it allows the sectors to be overwritten. Acronis True Image backs up the sectors from the special buffer, so that all the sectors of the point-in-time view of the system volume will be backed up intact. Meanwhile, the operating system continues working and the user will not notice anything unusual in the operating system functionality.

    Best regards,
    --
    Dmitry Nikolaev
     
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