Sunday, July 22, 2007

Issue while configuring CCR with FSW (File Share Witness)

I want to share with you one of the issues that I found during Exchange Server 2007 – CCR Implementation. The issue appears while trying to configure FSW (File Share Witness) for the CCR, I don’t know if anyone faced this issue or problem before during his testing of CCR , but in case you didn’t , and you faced the same issue, I am sharing the solution of this issue with you in order to get over and solve this issue.

What is FSW ?

CCR uses the new File Share Witness feature introduced in an update to the Windows 2003 SP1 to act as the witness node instead of implementing a third node in the cluster for that purpose. Microsoft always recommends to install the FSW on one of the Hub servers. Also in site resilience implementation MS recommend to pre-provision another FSW on the Hub server that is hosted in the backup site and to be used to speed up the process of bringing up the backup site in case of disasters, and in order to facilitate such process of bringing up the other FSW and as a best practices MS recommend to use a CNAME record that is pointing to the server hosting the FSW so in case of disasters you just need to change the CNAME record to point to the other server hosting the standby FSW, easy task. so in general you will create the CNAME record in the DNS that will be pointing to the FSW server, and the issue is in this procedure.

So where is the problem???

sometimes when you try to use the CNAME record to populate the FSW or even to test the access to the FSW share using the CNAME you will got this error:


”You were not connected because a duplicate name exists on the network. Go to System in Control Panel to change the computer name and try again”

For example, if you deployed FSW on a HUB Server called (SRV-E2K7HUP-01) and you added a CNAME Record under the Active Directory called FSW, and you tried to access this CNAME from any of the CCR Nodes under this network, by running file://fsw/ from Rum Command, you will get the above mentioned error, and you will not be able to proceed, cause you need to configure Windows Cluster for the Two CCR Nodes with file://fsw.domain/MNS_FileShare_Name. and both CCR nodes needs to access this shared folder.

The Solution:

To solve this problem you have to disable the Strict Name Checking, from the Registry of the server that hosts the FSW (which is in our case the HUP Server SRV-E2K7HUP-01):

  • Start Registry Editor (Regedt32.exe).

  • Locate and click the following key in the registry: HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\LanmanServer\Parameters.

  • On the Edit menu, click Add Value, and then add the following registry value:

    Value name: DisableStrictNameChecking
    Data type: REG_DWORD
    Radix: DecimalValue: 1

  • You have to restart the server after that.

  • After Restarting the server make sure that you can access the C-Name of the FSW Hosting Server from the Run command on both CCR Nodes.

Please let me know if anyone faced this problem before and could solve it with the same above steps, and if you could not test this on a CCR Environment, please try it now, so you will be familiar with the steps shown above.

I hope the above information is useful to you, and hope to bring again another more issues which might help you with Exchange Server 2007.