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  1. #1
    Senior Member JJZolx's Avatar
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    Windows Users: Run a full library scan following time changes

    There's an odd Windows "anomaly" where after a system time change, all of file date/times reported by the operating system will have changed. If you pay attention this can even be seen in Windows Explorer, where file modification times will shift one hour following a daylight savings time change.

    Whenever SlimServer/SqueeeCenter accesses any music file on the server it checks the file modification timestamp against what it has stored in its database. If it sees a difference, it will rescan the file and update its database. The effect this has is to cause a lot of unnecessary overhead when browsing and playing the music library. Whether or not you see a slowdown in response times of either the remote, web, or controller interfaces will probably depend on the speed of your server.

    So, IMO, it's a good idea to run a full clear/rescan following a Daylight Savings time change if you're running SS or SC on a Windows server.

  2. #2
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    Hmmmm.

    Is UTC time stored, or local time ?

    Window's isn't changing the time of the files - a given application (like explorer) gets timezone adjusted dates based upon the user's timezone settings.

  3. #3
    Senior Member JJZolx's Avatar
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    Quote Originally Posted by MrC View Post
    Hmmmm.

    Is UTC time stored, or local time ?

    Window's isn't changing the time of the files - a given application (like explorer) gets timezone adjusted dates based upon the user's timezone settings.
    No, Windows isn't modifying the times of files. In NTFS file systems UTC is stored. But what happens is that the timezone offset is changed when DST begins and ends.

    Here's an article that explains the problem, and even the reasons why Microsoft chose to implement it as they have.

    http://www.codeproject.com/KB/datetime/dstbugs.aspx

    I'm not sure if SqueezeCenter could work around the issue. I think it would depend upon whether ActiveState Perl can return pure UTC file times and then SC store those instead of local times.

  4. #4
    Ben Sandee
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    Windows Users: Run a full library scan following timechanges

    On Tue, Mar 11, 2008 at 9:57 PM, JJZolx <
    JJZolx.3652pz1205290801 (AT) no-mx (...limdevices.com> wrote:

    > Here's an article that explains the problem, and even the reasons why
    > Microsoft chose to implement it as they have.
    >
    > http://www.codeproject.com/KB/datetime/dstbugs.aspx
    >


    That is a really funny article...


  5. #5
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    Indeed, thanks for sharing.

  6. #6
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    Would this apply if NTFS Timestamp function disabled in WXP?

    .

  7. #7
    Senior Member JJZolx's Avatar
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    Quote Originally Posted by haunyack View Post
    Would this apply if NTFS Timestamp function disabled in WXP?
    Yes.

    The NtfsDisableLastAccessUpdate setting is supposed to be a performance tweak, correct?

    http://www.microsoft.com/technet/pro....mspx?mfr=true

    This only disables updating of last-access times (and I think it only applies to directories, not files). SqueezeCenter stores file last-modified timestamps in its database, not last-access.

  8. #8
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    Quote Originally Posted by JJZolx View Post
    Yes.The NtfsDisableLastAccessUpdate setting is supposed to be a performance tweak, correct?
    Yes, that is what is promulgated but I have not seen any quantifiable data to prove that out, nor do I notice any performance gain.
    The improvement is probably measured by nano/pico seconds saved and claimed as performance increase.

    This only disables updating of last-access times (and I think it only applies to directories, not files). SqueezeCenter stores file last-modified timestamps in its database, not last-access.
    Good to know...thanks for the info as I noticed that my usual re-scan took about 45 minutes longer than expected the night of the time-change.

    .
    Last edited by haunyack; 2008-03-11 at 21:43.

  9. #9
    Senior Member JJZolx's Avatar
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    Quote Originally Posted by haunyack View Post
    I noticed that my usual re-scan took about 45 minutes longer than expected the night of the time-change.
    If you were running a "new and changed" scan then it probably ended up rescanning every file in the library.

  10. #10
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    Quote Originally Posted by JJZolx View Post
    If you were running a "new and changed" scan then it probably ended up rescanning every file in the library.

    Yes, I add music regularly by using the My Music\<folder\album> method.
    After that I initiate a scan for MIP integration.
    I noticed that when I executed a backup next day, all my previous music files reported date & time change.
    Subsequently, I may have accidentally avoided the slowdown you mentioned by enduring the extra time needed to update the db.
    What luck!

    .
    Last edited by haunyack; 2008-03-11 at 22:55.

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