Dear Reader,
At one of our customer sites we are experiencing a strange problem. This is an SBS 2008 R2 x64 updated with the latest needed patches. Due to Dental software we are forced to have SMB 1.0 enabled on this server so we have done this to enhance the file sharing with the software. What we now experience is that after 1 or 2 days of working on this server the terminal server users can't start the network programs anymore (dental software). The local domain users who log on to the server can resolve the UNC paths. But when we then Logon to the server through RDP and try to reach the shares on the server itself it fails to reach them. It is just unable to resolve the UNC path and therefore remote site's can't work. To resolve this issue we have to restart the server and it works again.
Our setup is:
- Windows 2008 R2 x64 (SBS) with 25 XP SP3 Dutch clients;
- SMB 1 enabled;
- 2 NIC's both onboard (Intel 82574L) One of them is disabled and the driver version is 11.4.7.0;
- AVG 8.5.449 Anti-Virus;
TCP Global Parameters
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Receive-Side Scaling State : enabled
Chimney Offload State : automatic
NetDMA State : enabled
Direct Cache Acess (DCA) : disabled
Receive Window Auto-Tuning Level : normal
Add-On Congestion Control Provider : ctcp
ECN Capability : disabled
RFC 1323 Timestamps : disabled
For the rest it's a default out of the box installation of the server. To enable ourselves to test this setup we've build a server just like it in our office and have put an acronis image on the server itself to try and reproduce the errors. The problem here is the server is still able to reach itselve after 11 days so far. So we think it has something to do with a number of tcp/ip connections after which it becomes unreachable. Nothing strange shows up in the Eventviewer of the Windows server.
Do you have any idea of what this could be? Is there a benchmark/stress tool which emulate's clients/connections to try and force this to happen on our test server? Is there a maximum session limit when using SMB 1 forced on a 2008 R2 server? I did find an article here http://www.petri.co.il/forums/showthread.php?t=31139&page=2 which mentions a registry key with some threads and workers. Allthough it doesn't mention anything about the type of value and where to exactly put them.
Also I found http://www.petri.co.il/forums/showthread.php?t=25791&page=1 This is exaclty our problem but we do not have Symantec anti-virus installed. I did find a post in there stating that it happened when a client triggered 1000 connections to the server. Is this a possible overflow on a max connections setting?
Best Regards, Tim.