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  1. #1
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    Pluses or Minuses NTFS File Compression XP Pro SP1

    I just wanted to get a consensus/perspective on NTFS file compression, because I keep seeing a mixed picture. I have heard multiple tech support at Exec Soft say they are unanimously against it because it can cause "file damage" and very slow access and not to ever do it. I have seen threads/articles saying it can actually speed access as well as save space. Three examples and two MSKBs are here:

    User Tip #142: Windows NT NTFS Directory Compression
    Compression on NTFS Virtues and Vices
    Data Compression from Exec Soft Technical Director

    251186: Best Practices for NTFS Compression in Windows
    307987: HOW TO: Use File Compression in Windows XP

    SMBP

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    Re: Pluses or Minuses NTFS File Compression XP Pro SP1

    Compression is now little used because it's not needed - so by definition it is less tested than most other parts of the operating system. Disks are now very cheap. Why bother with something that uses amounts of CPU when for a few $ more you can get a much bigger disk?

    I would avoid compression as an unnecessary complication. (Similarly encryption, unless you're GCHQ - in which case you'd have a stronger mechanism anyway!).

    IMHO.
    <font face="Script MT Bold"><font color=blue><big><big>John</big></big></font color=blue></font face=script>

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  3. #3
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    Re: Pluses or Minuses NTFS File Compression XP Pro SP1

    I have to agree with John on this. With 300GB hard drives around the corner and all drives selling at all time low prices, why compress anything except your system and data backups ?? And even then, it almost makes sense to just copy your entire system to another hard drive as is.
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    Re: Pluses or Minuses NTFS File Compression XP Pro SP1

    I agree with John and Doc, there is no use for this compression with the hard drives that we have to day. Also it will slow down the system because each file will need to uncompressed to be used anfd then compressed when put away.

    Now running HP Pavilion a6528p, with Win7 64 Bit OS.

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    Re: Pluses or Minuses NTFS File Compression XP Pro SP1

    When you read compressed data you actually have to transfer less data from the disk. I have heard a theory that modern CPUs are so fast that the time taken to decompress/compress is significantly less than the disk access time that it saves. If this is true then compression may actually lead to a speed increase. I have never carried out any experiments to see if this really is true - and I was fairly sceptical when I heard it.

    StuartR

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    Re: Pluses or Minuses NTFS File Compression XP Pro SP1

    Stuart,
    There was a thread last year (April or May I believe) about allowing the Disk Cleanup utility to compress unsued files and folders (Windows choice which files were to be compressed). Several loungers noted that when they selected this option, that in a rather short time their machines slowed to a crawl and took several hours to get straightend out. There was a reg hack posted to eliminate this option in Disk Cleanup and it eliminated the problem. Compression, no matter how fast the CPU or the overall PC speed, is simply a waste of processing power.

    I can't imagine how it would enable you to transfer less data from the disk. Does it drop every third word from a document, or perhaps lower the resolution of an image ??? <img src=/S/grin.gif border=0 alt=grin width=15 height=15> I wouldn't even attempt to experiment with it. From all I've read and seen concerning compressed data, I'll leave that headache to someone else. <img src=/S/brickwall.gif border=0 alt=brickwall width=25 height=15>
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    Re: Pluses or Minuses NTFS File Compression XP Pro SP1

    Doc

    It would have to be lossless compression, like ZIP, not lossy compression, like JPEGs!

    Otherwise we would be going down the route that was suggested, apparently seriously, in the early days of PCs, when an infamous poster suggested that you could compress files multiple times (using, say, PKZIP) to make them smaller and smaller, but failed to see that the limit of this was one byte (or maybe even one bit!). How would one uncompress the resulting micro-file to obtain the original, if all you had to expand was one byte? (Needless to say the OP had not tried the test for himself...) <img src=/S/laugh.gif border=0 alt=laugh width=15 height=15>
    <font face="Script MT Bold"><font color=blue><big><big>John</big></big></font color=blue></font face=script>

    Ita, esto, quidcumque...

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    Re: Pluses or Minuses NTFS File Compression XP Pro SP1

    John,

    That theory sounds like the mulit-wrapped gift gag. The one where you buy a small gift and wrap it, then put the wrapped gift in a slightly larger box and wrap that, repeating the process until you have a box the size of a refrigerator that, when COMPLETELY unwrapped, contains a pair of earrings !!! Ultimately a complete waste of time !! Kinda like compressing your data. <img src=/S/yep.gif border=0 alt=yep width=15 height=15>
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    Re: Pluses or Minuses NTFS File Compression XP Pro SP1

    Doc

    Oh, I don't know -- I could give the earrings to Rebecca!

    John
    <font face="Script MT Bold"><font color=blue><big><big>John</big></big></font color=blue></font face=script>

    Ita, esto, quidcumque...

  10. #10
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    Re: Pluses or Minuses NTFS File Compression XP Pro SP1

    John,

    But what would you do with the refrigerator ??? <img src=/S/grin.gif border=0 alt=grin width=15 height=15>
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    Re: Pluses or Minuses NTFS File Compression XP Pro SP1

    Thanks very much Doc, Dave, John and Stewart. I could read all over the place but getting this kind of perspective from people who have watched this for years is worth far more.

    SMBP

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    Re: Pluses or Minuses NTFS File Compression XP Pro SP1

    Doc,

    The issue with CPU speed and disk speed occurs because the compressed data takes up less space on disk. For example, ff you try to read 5 MBytes of data from a large file you may read 3MBytes of disk data and then expand this to 5MBytes. There clearly is a trade off where slow enough disk access and fast enough CPU and memory would make this worthwhile.

    I have never done any testing of this, but it is certainly credible.

    StuartR

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    Re: Pluses or Minuses NTFS File Compression XP Pro SP1

    But the expanded file must then be in RAM or the cache which in turn is taking more time to load.

    Now running HP Pavilion a6528p, with Win7 64 Bit OS.

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    Re: Pluses or Minuses NTFS File Compression XP Pro SP1

    Stuart,

    Point well taken. I can see that there is a credible argument for that hypothesis. I would wonder though, if it is faster to access and use compressed data, if that is how the "super computers" process data so quickly. I've never read anything on that subject.

    On the other hand, Dave's point has merit too.

    And around and around we go. <img src=/S/smile.gif border=0 alt=smile width=15 height=15>
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    Re: Pluses or Minuses NTFS File Compression XP Pro SP1

    Sure, but it was going to get to memory anyway. The discussion is whether it is quicker to load 5MBytes of memory from disk, or to load 3 MBytes from disk and decompress it to create 5 MBytes of in memory data. Clearly there is a point where the CPU amd memory are so much faster than the disk that this is a worthwhile trade off, I just don't know if that is ever true for modern hardware.

    I'm starting to regret mentioning this one.

    StuartR

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