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We are having a strange issue with Directory.GetFiles method trying search for a Word Document from a UNC Folder Share (NTFS Disk) on a Win2008R2 VMServer. The share contain over 10K Files in the Parent Folder and 75K Files in a SubDirectory.

It was all working fine in Win2003 Server. When migrated to Win2008R2 Server, the WinForms application freezes over this method and taking almost 13 minutes to Open a single File from a Client machine connected to the File Share via a VPN Network that has Download Speed bandwidth of 1Mbps (not throughput).

After search & research, we realized the Windows Search service was not turned on and the Service was started and the share was indexed. We saw a performance improvement where the time taken to open a file using GetFiles Method came down to 3 Minutes from 13 minutes.

But this is not consistent. During day time when bandwidth is much lower than 1MBPS (say 0.5 MBPS) the time-span to open the document is again between 8-12 minutes.

At this point we are not sure of which one is causing the problem?

Not possible solutions: 1) Creating multiple directories and organizing files. 2) Increasing bandwidth. 3) Using direct filepath instead of Directory.GetFiles/EnumerateFiles

Any help is highly appreciated. Thanks!

iCode
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Oh yeah, good stuff. You will notice that even if the service is off, running it twice (within a short tiem of each other) will run much faster the second time. Actually, here is a good one for you, run it twice, let the first one run for a minute. The second one will catch up the first one almost immediately and then they will both be at the same spot for the rest of the time. (if what I said makes sense).

Here is what is happening, GetFiles() and GetDirectories() do use the indexing service. Also, if your indexing service is off, this just means it will not automatically get data about the files, but when you access the file (windows explorer / GetFiles) it will index them, so that if you ask for the same thing with a set amount of time, it wont have to query the Hard-Drives' Table-Of-Contents again.

As far as it running faster and slower when the indexing service is on, this is because windows knows it cannot keep track of every file on the computer. Therefore, after a set amount of time, the file is considered stale and the indexing service will do an IO call to get the info to update the index database, when you ask about the file.

This wiki talks about it, just a little. Not very thorough.

Steve
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  • Hi Steve, Thank you for the detailed answer. Very informative. Indexing service was indeed playing a crucial role. But it was also the inconsistent network speed that added to the problem. At this point, the issue is temporarily resolved and we may look for a much better implementation of handling files and folders in future. – iCode Oct 21 '13 at 22:15