Disabling/Reducing File Copy cache on XP Pro x64 ?

Discussion in 'other software & services' started by Defenestration, Feb 19, 2008.

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  1. Defenestration

    Defenestration Registered Member

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    Sometimes when I copy several large files on XP Pro x64, the copy takes no time at all due to Windows caching the files in memory (over 1GB in some cases), with the copy continuing in the background. This means that the progress dialogs don't show a true indication of the progress.

    I've only noticed this since using XP Pro x64 (ie. re-badged Windows Server 2003), and am assuming it's some kind of feature of the Server OS, as opposed to the Desktop OS. This "extreme" caching still occurs when the destination drive is one of my USB external drives, which has been optimized for quick removal (which supposedly disables caching), so there must be another setting somewhere.

    Does anyone know how I can disable this Windows caching behaviour so that progress dialogs show a true indication of copy progress ?
     
  2. NGRhodes

    NGRhodes Registered Member

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    Your removable drive will have write caching disabled, but it does not stop read caching from any other drive.

    Why is the dialog more important than perforance to you ?
    How do you know that disabling the cache will fix it ?

    The progress of the dialog is only an estimate, you can never guarantee 100% disk access time on a multitasking OS, there are caches built into drives and the peformance of files varies depending on placement on the phyisical disk, then you have the fact that the dialogs are not updated in realtime (and gets delayed when there is cpu activity from another process) - there simply are too many variables to make the dialog progress accurate.

    There are some specific tools, like cacheman, but I have never tried any.
     
  3. Defenestration

    Defenestration Registered Member

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    The dialog is not more important than performance, and the cache has not sped up the copy as such, it's simply sped up the read part. The problem is that aside from looking at the hard disk light, it's not possible to tell when a copy/move has finished. This has implications in that I might decide to reboot while the copy is still going on, causing data loss, I imagine.

    Also, when copying/moving multiple files, it's not possible to tell which files have finished and which are still in the process of being copied/move.

    I agree the progress can never be 100% accurate, but with much smaller caches they are pretty accurate. With massive (ie. over 1GB) caches being used, the progress dialogs lose all meaning. By stopping Windows from using such a large cache (read cache in this case, as you pointed out), disabling, or reducing the size of this cache will remove the problem (I hope :) )
     
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