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  1. #1
    Senior Member Diana's Avatar
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    What counts as 'new and changed music'?

    Friends >>> I've been having some problems with scanner.exe, which has been hanging part way through scans. After a clean install of a 6.5.1 nightly, the 'clear and rescan' now works fine. But 'look for new and changed music' still results in scanner.exe stalling so that I have to shut it down manually - when I can: it sometimes hangs Windows, too, and a 'press and hold power switch' is the only answer.

    I'm now mostly only rescanning after I edit some tags, move some files from one directory to another, or edit some filenames. Might these changes be more than 'Look for new or changed music' can cope with?

    I'd be grateful for an explanation of the difference between the two sorts of scan. I'd also be grateful to know if there are limitations on the use of 'look for new and changed music'. Suppose an expert user was going to do a rescan: what would decide that person to use one sort of scan rather than the other?

  2. #2
    Senior Member JJZolx's Avatar
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    Quote Originally Posted by Diana View Post
    Friends >>> I've been having some problems with scanner.exe, which has been hanging part way through scans. After a clean install of a 6.5.1 nightly, the 'clear and rescan' now works fine. But 'look for new and changed music' still results in scanner.exe stalling so that I have to shut it down manually - when I can: it sometimes hangs Windows, too, and a 'press and hold power switch' is the only answer.

    I'm now mostly only rescanning after I edit some tags, move some files from one directory to another, or edit some filenames. Might these changes be more than 'Look for new or changed music' can cope with?

    I'd be grateful for an explanation of the difference between the two sorts of scan. I'd also be grateful to know if there are limitations on the use of 'look for new and changed music'. Suppose an expert user was going to do a rescan: what would decide that person to use one sort of scan rather than the other?
    Can't help with the crashes, but I'll take a crack at answering best I can. The following explanation assumes you don't use iTunes or MusicIP, each of which appears to cause a whole other class of bugs when it comes to scanning.

    A clear/rescan completely deletes everything in the SlimServer database and starts all over. This is still the best was of making sure the data in the SlimServer database matches your actual music library. From what I can tell there's no difference in the time it takes to run a clear/rescan vs a new/changed scan. The only practical difference is that with a new/changed scan you can continue to browse and listen to your music while the scan is running.

    One issue with a clear/rescan that seems to be ongoing is that while you'd _expect_ it to essentially give SlimServer a fresh view on things, SlimServer's caching of files and artwork can cause problems.

    A new/changed scan keeps the data in the database while it goes through the library looking for changed files, new files and deleted files and updates the database accordingly.

    New files are files for which a reference doesn't exist in the database. My experience is that the scanner never screws up cataloging new files in a new/changed scan.

    Changed files are files that have a different modified timestamp than the one in the database. Same location (directory path) and filename, but different times. I would assume that it doesn't matter if the timetamp on the file is newer or older. The scanner is good at picking these up, but if you've changed tag data then old data often remains in the databse and can cause confusion. The scanner isn't very good about removing data that should be deleted from the database. For instance, if you had a single album by "Johny Cash" and then retagged all the tracks to read "Johnny Cash" you'll likely end up with both versions of the artist name when you browse.

    Deleted files are files that no longer exist. Like changed files, the scanner isn't particularly good at removing the data that should be removed from the databse.

    One thing to keep in mind: Whenever you rename files or folders, or you move files to a different foler, it's the same thing as deleting files and then adding completely new files. The scanner is likely to pick up the "new" files and read their metadata, but it may not remove the old data.

  3. #3
    Senior Member Diana's Avatar
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    Jim >>> Thanks ever so much for a very clear and comprehensive summary - it was really helpful.

    I think I will take your hint, and stick to 'clear & rescan' as the most reliable method of updating the library. This does not take long, as I only have three thousand or so tracks.

    As 'clear and rescan' seems to operate without stalling or crashing on my system, I won't bother trying to untangle the problem with 'look for new/changed' - so you've also saved me a lot of time and hassle.

    It was good of you to spend time on this. Thanks again!

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