New SAN causes HTTP 414 error

We have a IIS virtual directory (/Upload) mapped to a DFS share, which resides on a SAN. The DFS share was moved from SAN A to SAN B and since then if we try to access any content via the virtual directory, we get the error: HTTP Error 414.0 - The page was not displayed because the Request URI is too long.

We have tried different DFS shares and also accessing the SAN directly via its network name, but neither have worked.

We are able to browse the DFS share via Windows Explorer from the servers (2 live, 1 dev, all Windows 2008 R2).

We are using a 3rd party module for image resizing, http://imageresizing.net/, if we point to a image that is in the virtual directory it will return it, e.g. /upload/test.jpg.ashx?width=100, where as /upload/test.jpg will return the above error.

I think the error message is misleading and we have done a failed request tracing and the error logged is:

ModuleName: IIS Web Core
Notification: 2
HttpStatus: 414
HttpReason: URL Too Long
HttpSubStatus: 0
ErrorCode: 2147942487
ConfigExceptionInfo
Notification: AUTHENTICATE_REQUEST
ErrorCode: The parameter is incorrect. (0x80070057)

We have now tried it on a Windows 8 machine, with IIS 8, mapped the virtual directory in the same way and it works.

The issue was resolved when the SAN provider finally acknowledged that there is a known issue. They supplied us with a patch, which meant IIS versions <= 7.5 were able to serve files from our SAN.