dangerous to create drive image with system running?

Discussion in 'Acronis True Image Product Line' started by kavelot, Dec 13, 2008.

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  1. kavelot

    kavelot Infrequent Poster

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    hello
    I always though it would be dangerous to create a drive image with the system running

    consider this example:
    I have a database program running, let's say MySQL, while I'm running Acronis... and MySQL stores a table on file names.tbl

    then:
    1) Acronis checks this file is stored on clusters 1000 to 1200
    2) it backs up clusters 1000 to 1050
    3) MySQL changes clusters 1080-1100
    4) Acronis keeps backing up clusters 1051-1200

    now Acronis mixed old data with new on its backup file

    so, the question is... how it deals with that?
    or it doesn't? (ie, I should shutdown programs that writes to the disk before running Acronis)

    thanks
     
  2. NumLock

    NumLock Registered Member

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    Think of it like taking a picture. If you take a picture of a person running then you have a blurry image, but you will get it developed. When backing up the database it is best to stop it temporarily whilst taking the 'snapshot' and then resume it once the 'development' starts. You can the database pre and post commands to achieve this.
     
  3. Acronis Support

    Acronis Support Acronis Support Staff

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    Hello kavelot and NumLock,

    Thank you for using Acronis Corporate Products

    kavelot, what is the exact title of Acronis product you are using? What is your operating system?

    I may recommend you to use our Live Chat service here. We can find a most pertinent solution for you.

    Thank you.

    __

    Oleg Lee
     
  4. shieber

    shieber Registered Member

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    ATI takes a snapshot of the drive when it starts a backup; filters the writes that occur after the snapshot is taken. So any changes made to the source dirve after the backup starts are not inlcuded in the backup; the backup has only the data present at the start of the backup. To backup up subseqentyly written data, you would need to to do a subsequent backup.
     
  5. seekforever

    seekforever Registered Member

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    I think this answer is going to have to come from Acronis since a database program is involved. I don't know the current status but in earlier versions database applications required more than the home version to properly lock the system without losing queued records.
     
  6. stbi

    stbi Registered Member

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    That's what I initially wanted to ask in this posting: If changes are made to the file system while it's being imaged, then is the image consistent as a whole? If so, then OK, but I wasn't able to find infos on that in the documentation. Perhaps I should simply test it...
     
  7. Acronis Support

    Acronis Support Acronis Support Staff

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    Hello all,

    Thank you for your interesting in Acronis True Image

    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
     
  8. stbi

    stbi Registered Member

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    Thanks for your answer. So if the data is changed on one partition during the backup, the image is logically consistent. However, if more than one partition is backed up, each partition in the image file has a different "time stamp"; so if, for example, the files of a database are distributed across two partitions, they aren't necessarily consistent in the image, right?
     
  9. Acronis Support

    Acronis Support Acronis Support Staff

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    Hello stbi,

    Thank you for your interesting in Acronis True Image

    In case data is distributed between two partitions the integrity of backup image is depend on what moment snapshot was created. In case it was created after changes between two partitions then data will be included into the image.

    Best regards,
    --
    Dmitry Nikolaev
     
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