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I'm running into some problems with a file share used by an ASP.NET web application. With this configuration, there are 2 web servers (win2k8 web) that connect to a file server (win2k8 enterprise), reading and writing files using a file share. Recently, one of the web servers has begun encountering an error accessing the file share:

 IOException: The specified network name is no longer available.

There does not appear to be much info on the web for explaining what's causing this and how to best fix it, so I'm looking at what I can monitor in order to get clues. I'm not sure if it's hardware, just a load issue, file size, frequency, etc.

With Windows perfmon, what can I monitor on the File Server side? There's the "Files Open" object, any other good ones?

What can I monitor on the web server side?


I'll add that the UNC path uses the IP address of the file server, not a name to resolve. Also the share is a single, flat directory with over 100K files.

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Problems with that kind of message tend not to be file-SYSTEM problems, more file-SERVER issues. Or even web-server issues. That error is generated when the web-server can no longer talk to the file-server for some reason. Perhaps the pre-existing connection got reset and hasn't renegotiated yet. Perhaps name-resolution on the web-server is broken to the point where \\server\fileshare no longer can be resolved into something connectible. Both of these cause the above message and don't have any counters in perfmon.

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I agree it could be name resolution, but I also want to rule out the possibility of SMB connections being used up. I saw one article suggest monitoring "Redirector\Current Commands" from the client side, but that doesn't budge as I'm working with files in the web app. –  RyanW Jan 31 '11 at 19:20
@RyanW SMB connections won't exhaust for a l-o-n-g time. Unless your web-farm is in the thousands of servers or you have that many app-pools, you shouldn't have to worry about it. One connection per web-server/app-pool/file-share combination. –  sysadmin1138 Jan 31 '11 at 19:26
yeah, everything I find confirms what you're saying, it should only be using 1 connection. I have the app pool identity set, so it should be reusing the app pool user's connection right? Does the number of files matter? over 100K files in a single flat directory. –  RyanW Jan 31 '11 at 20:37
@RyanW THAT could be an issue. Enumerating 100K files does take a while and may exceed web-app timeouts if the file-server itself is loaded enough. Open-file-handles, the number of simultaneously accessed files, is 16K per connection (2003) or larger (2008+) so that probably isn't an issue by itself. –  sysadmin1138 Jan 31 '11 at 20:44
OK, thanks for all the help. –  RyanW Jan 31 '11 at 23:16
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