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I've tried defragmenting my hard disk to see if Outlook performance improves. The .ost file shows 1000+ fragments but even after a post-defragmentation restart - never launching Outlook - it still shows that the file hasn't actually been defragmented.

Could this be contributing to slower Outlook performance? Any ideas how I can get the .ost file defragmented?

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up vote 5 down vote accepted

Is it 'normal'? Yes.

Can you defragment them? Yes, but you need an extra MS utility called "Contig" (short for Contiguous).

You can get Contig from here.

Tutorial (from here):

  1. Close the Outlook program.

  2. Click the "Start" button, then click the "Search" box. Type "*.ost" in the "Search" box and press the "Enter" key. Right-click the "OST" file displayed in the search results and click "Properties" in the menu that appears.

  3. Note the path to the "OST" file that is displayed in the "Properties" window that appears.

  4. Click the "Start" button, then click "Programs." Click "Accessories" and then right-click on the command line icon. Click "Run as Administrator" in the menu that appears.

  5. Type "cd c:\path_to_contig," substituting "c:\path_to_contig" with the actual path and directory where the Contig utility is located, then press the "Enter" key.

  6. Type "contig --v path_to_ost/filename.ost," substituting "path_to_ost/filename.ost" with the actual path and name for the "OST" file, then press the "Enter" key.

  7. Wait while the Contig utility processes the "OST" file. When the command line output confirms that the defrag operation has completed, you can start Outlook.

More info here.

Hope that helps...

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