Event Logs are Your Friends
They're here to help you! Look in the System event log for network related errors. I would not be surprised if there were errors from
Source: MrxSmb or
Network Monitor doesn't bite... too hard
Capture traffic from your network card and inspect the errors. In fact, set up Network Monitor on the troubled server as well as the endpoint you're trying to connect to. In Network Monitor, the TCP Retransmit option will show you retransmit statistics. In the Capture Statistics summary frame, I would wager a bet that you'll see some interesting traffic rejections or hardware errors.
For some more information, check out Microsoft KB325487.
What do the above two troubleshooting techniques prove?
You've got hardware issues. It could be any of the following
- Bad drivers on the server
- Bad BIOS in need of an update
- Motherboard / chipset drivers need updating
- the NIC and switch port are not negotiating nicely. Make sure that both are set for 10/100 full duplex or 1Gbit full duplex. Turn that auto-negotiate nonsense off. Whatever you do, make sure that both server NIC and switch port agree with each other (unless they both agree to negotiate - don't let them do that).
That is not an exhaustive list, but gives you a start.
SMB version 1 vs. version 2
Consider what OS your server is trying to connection to. Windows Server 2003 / XP and earlier use SMB 1, while Server 2008 / Vista and newer use SMB 2. To narrow the issue down, consider disabling one and then the other.
The registry hive to muck with SMB versions is
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\LanmanServer\Parameters In that hive, add a new DWORD value with the name
SMB2 and set the value to
0. That disables SMB 2. Then try to connect to shares and see what the result is.
If that "solves" the issue, then you may need to re-install some of the networking components of the OS.
Use the "Maximize throughput for file sharing" trick
As per the ServerFault Q/A titled "Intermittent connection to Windows
7 shared folder from Windows XP workstations" there's an old trick
on Windows machines involving "How to Optimize Windows NT Server Using
When you configure one of the four options for the Server service, the
information is saved to the following two registry keys:
Your choices for this registry key are 1,2 and 3. 1 = Minimize Memory
Used 2 = Balance 3 = Maximize Throughput for File Sharing and Maximize
Throughput for Network Applications
Your choices for this registry key are 0 and 1. 1 = Maximize
Throughput for File Sharing 0 = Maximize Throughput for Network
The above technique has been used in your situation to renew communication with SMB shares.
But above all...
INSPECT YOUR EVENT LOGS!
Seriously. They're awesome.