How does TI handle "unused" HDD sectors?

Discussion in 'Acronis True Image Product Line' started by gbark, Feb 18, 2005.

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  1. gbark

    gbark Registered Member

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    Other than a passing reference that TI doesn't image unused sectors, I was unable to find a satisfying answer using the forum search function.

    Since TI is recording a bit image of the HDD, how does it actually skip the swap file, hibernate file, etc.? The "mechanics" of the process is what I'm looking for (for lack of a better phrase o_O )

    For many months I've been using the following weekly routine:
    1. Empty Internet Explorer (IE) cache
    2. Run a "cookie" cleaner to kill off unwanted cookies.
    3. Run a utility to delete windows *.tmp, *.fts, *.gid, etc. files
    4. Empty recycle bin.
    5. Run "Eraser" to zero unused sectors and file "tails"
    6. Run TI incremental image
    This "pre-treatment" is like pre-treating your laundry. :rolleyes: It gets rid of stuff that I don't need imaged. Since TI compresses the data in the image, having all of the unused (erased and truly unused) sectors on the HDD holding all zeroes instead of leftover file flotsam and random data from the last partition reformat allows TI to compress the "stuff" to the absolute minimum size in the image.

    I'm sure that zeroing the file tails will continue to be useful, however I'm wondering if TI is actually skipping the portions of the drive that are marked "unused" in the FAT.

    I should mention that I'm using FAT32, not NTFS, but the question is (probably) still a valid one.

    So far, my incrementals have been averaging only 125-150 MB per weekly incremental image. If TI will actually skip these empty sectors I'd like to eliminate the "eraser" portion of my routine. It does cause the drive to run a bit warm and probably is more intensive data writing than the drive is expected to see in most cases.

    Any opinions, comments will be appreciated.
     
  2. Acronis Support

    Acronis Support Acronis Support Staff

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    Hello gbark,

    Thank you for your interest in Acronis True Image (http://www.acronis.com/homecomputing/products/trueimage/).

    When you create the image of a partition with known file system (FAT, NTFS, Ext2, Ext3 etc.) Acronis True Image reads the file table of the partition where it is shown which sectors are used and which are not. From this file table it also can conclude where the hybernation and paging files are resided so that Acronis True Image can avoid imaging these sectors.

    Thank you.
    --
    Ilya Toytman
     
  3. gbark

    gbark Registered Member

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    Thanks Ilya,

    Although my swap file is located in a separate partition on a different drive than my OS, apps, and data, TI's ability to skip the swap file is a great feature that I often mention when recommending TI to friends.

    What about the unused (erased as well as not yet used) sectors on a drive? It seems as if TI could use the same logic to identify the sections of the drive that contains unused sectors and skip them as well.

    I'm curious because one week I failed to run Eraser to zero the erased file sectors and my TI incremental image file seemed notable larger than usual. Here's a copy of a section of the TI user's manual:
    It was this text that led me to believe that TI might skip unused sectors.
     
  4. Acronis Support

    Acronis Support Acronis Support Staff

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    Hello gbark,

    Acronis True Image does skip unused sectors if you use the known file system (FAT32 and NTFS are two examples). In this case you don't need to erase unused sectors. The incremental image size strongly depends on whether you have changed the content of the sectors even if it was done not by yourself but by operational system or any application. This may be the reason for the size increase you described.

    Thank you.
    --
    Ilya Toytman
     
  5. gbark

    gbark Registered Member

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    Thanks again Ilya,

    It looks like I may be able to skip the erasure of my deleted file space. I was erasing using zeros rather than pseudorandom data because I was more interested in reducing incremental image size than I was in security. A bunch of sectors full of zeros will compress more than any actual data would.

    I think I'll try erasing only my file tips (and probably my IE cache folders too, just in case ;) ) and see how the file size looks.

    Thanks for the information. :)
     
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