Different in File Size & Size on Disk

Page 1 of 2 12 LastLast

  1. Posts : 26
    Windows 7 Build 7600
       #1

    Different in File Size & Size on Disk


    I'm transferring files, from external hard disk to an another external hard disk...
    from a non-external powered to an external powered one...

    I'm using cut & paste...

    Suddenly, blackout happens...

    There'll be data writing failure...

    So I checked some of my files(mostly in .iso)... Some of them have very big difference between Files Size & Size on Disk (around 4 GB)...

    So, I tried to open it... Nothing happen...

    Does this big difference can make anything goes wrong?
      My Computer


  2. Posts : 761
    Windows 2000 5.0 Build 2195
       #2

    Are you talking about this?
    Attached Thumbnails Attached Thumbnails Different in File Size & Size on Disk-.png  
      My Computer


  3. Posts : 26
    Windows 7 Build 7600
    Thread Starter
       #3

    Yup... but in your picture, the difference in not too big... but what happen to me is there value difference is about 4GB
      My Computer


  4. ryo
    Posts : 1,953
    windows 7
       #4

    iUnique said:
    Yup... but in your picture, the difference in not too big... but what happen to me is there value difference is about 4GB
    lol...did you use winzip or winrar??
      My Computer


  5. Posts : 26
    Windows 7 Build 7600
    Thread Starter
       #5

    use PowerISO of course...
      My Computer


  6. Posts : 761
    Windows 2000 5.0 Build 2195
       #6

    EDIT: Considering the power outage, try doing a chkdsk /f and see if it find errors, else you'll have to copy the files all over again.

    -Original post by me:
    Two possibilities: Compression using the default windows .zip interface and sector size. I would go with the latter. It's like this:

    Compression is fairly easy to explain. "Size" dictates what the actual size is, and the "size on disk" dictates how much space it is occupying the hard disk after being squished in to a very small size.

    Sectors are a bit more complicated. Your hard drive is divided in to many, many things. The smallest and most important are the sectors. Think of sectors as honeycombs in a bee's hive. They combine together to form an actual hive of honey.

    Now, Windows 7 has a default sector size of 4KB. That means that for every block of data, it divides it into a 4KB pieces. Now if you have a 6KB file, the first 4KB will occupy sector 1. The next 2KB will occupy sector 2. You cannot add another file on sector 2 since it is already occupied by a file. Considering that, file 1 is actually occupying 8KB even though it is only 6KB.

    To give you an example, I'll show you a screenshot of my PC. My sector size is at 32KB (the bigger, the better in performance :P)


    See how even if it's 1 byte it takes up 32KB? It's because of my sector size.


    That's a loss of 32,767 bytes. Of course, the effect stacks up. Now see what happens when I copy that file 237 times.



    Hopefully that should give you a basic understaning on why there's a big difference on "Size" and "Size on disk".
    Last edited by arkhi; 07 Apr 2010 at 22:12.
      My Computer


  7. Posts : 5,642
    Windows 10 Pro (x64)
       #7

    Durning the copy process, Windows probably made sparse files to pre-allocate large block for the file to be written to. Which might accound for the difference.
      My Computer


  8. Posts : 1,170
    XP Pro SP3 X86 / Win7 Pro X86
       #8

    iUnique said:
    I'm transferring files, from external hard disk to an another external hard disk...
    from a non-external powered to an external powered one...

    I'm using cut & paste...

    Suddenly, blackout happens...

    There'll be data writing failure...

    So I checked some of my files(mostly in .iso)... Some of them have very big difference between Files Size & Size on Disk (around 4 GB)...

    So, I tried to open it... Nothing happen...

    Does this big difference can make anything goes wrong?


    You had a power failure...

    The file is incomplete on your destination disk and yes the size difference matters *A LOT*. What you should do is delete the incomplete file and copy it over again.
      My Computer


  9. Posts : 26
    Windows 7 Build 7600
    Thread Starter
       #9

    You had a power failure...

    The file is incomplete on your destination disk and yes the size difference matters *A LOT*. What you should do is delete the incomplete file and copy it over again.
    But the prob is, I was moving the file, not copying the file... when I checked back the original hard drive, the file is gone.. but it present in the destination hard drive... have same file size (as what I have remembered)... But I'm getting suspicious about the file size & size on disk... By the way, the file is .iso, when I opened it with PowerISO, I get no error message... It means that there's no prob at all, am I right?

    So, the file is actually normal, right?
      My Computer


  10. ryo
    Posts : 1,953
    windows 7
       #10

    why you not try use other...dont use powerISO..

    compare it.
      My Computer


 
Page 1 of 2 12 LastLast

  Related Discussions
Our Sites
Site Links
About Us
Windows 7 Forums is an independent web site and has not been authorized, sponsored, or otherwise approved by Microsoft Corporation. "Windows 7" and related materials are trademarks of Microsoft Corp.

© Designer Media Ltd
All times are GMT -5. The time now is 01:18.
Find Us