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Does losing access to File Share Witness in CCR can cause Exchange Server to failover ?

Hi All,

I have placed the File Share Witness in one of the Hub Transport server for my Cluster Mailbox Server (using CCR).
All in a sudden the cluster failover itself to the passive node in DR site.

How is that possible ?
According to the network team and VMware Team, there was no outage in the network nor there is problem in VMware Hypervisor layer. I can see that there was no error logged in the network status and VMware vsphere console.

Any idea would be greatly appreciated.

Thanks
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Senior IT System Engineer
Asked:
Senior IT System Engineer
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3 Solutions
 
Adam FarageEnterprise ArchCommented:
So.. lecture time :D (good kinda lecture, not bad! promise)

A CCR cluster is simply a two node Exchange cluster utilizing (in the backend ) the Windows Failover Clustering bits that tie into the DLL's for Exchange. Since you cannot have a two node cluster all by itself, you would need a tie breaker vote (e.g: file share witness) so if one of the two nodes of the cluster goes down, the cluster is still alive as you have 2 / 3 votes (node majority).

In your situation it sounds like one of the two nodes is not able to contact the file share witness. If this is the case, I would look through the cluster logs (I would have to find the location for the version of Windows server you are using, but they are the failover cluster logs .. you may need to have cluster debugging enabled, I cant remember off the top of my head) to see what happened, but it is typically either a network issue (where the switch or port is dropping packets intermittently, or the SYN packet from the FSW / Cluster Owner is not responding in enough time) or a network consumption issue on the server that is failing over (meaning, for some reason the server is not responding to the SYN RPC request from the cluster owner or the FSW, and the cluster thinks the server is down). I would review the actual health and utilization (resources + networking) to see if either one of these are the issue.

Furthermore, you may also want to check to make sure the FSW is fully functional and properly configured: http://technet.microsoft.com/en-us/library/bb124922%28v=exchg.80%29.aspx. I doubt honestly this is the case, because if the cluster failed over then one of the two nodes was not available or responding to requests, and at that point I believe the whole cluster would have went offline due to lack of majority vote.
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Senior IT System EngineerIT ProfessionalAuthor Commented:
Thanks for the assistance Adam.

What is the required AD account and permission that I need to put into the FSW NTFS share & directory security ?
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Adam FarageEnterprise ArchCommented:
See under service account requirements (the last section of the article): http://technet.microsoft.com/en-us/library/aa996568%28v=exchg.80%29.aspx

If the CCR solution is deployed on Windows Server 2003, the Cluster service account must have local administrator privileges on the cluster nodes.

If the CCR solution is deployed on Windows Server 2003, you must use a domain account for the Cluster service account, and all nodes in the cluster must use the same Cluster service account.

All nodes in the cluster must be members of the same domain
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Senior IT System EngineerIT ProfessionalAuthor Commented:
Well, the Servers are all WIndows Server 2008 SP2 the AD domain is just one, no other domain.

So do I need to add my Domain Admin account as well so that I can open the FSW shared folder from both Exchange Mailbox server ?
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Adam FarageEnterprise ArchCommented:
No. The Cluster Service Account should be apart of the Exchange Trusted Subsystems, if that group is available.
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Senior IT System EngineerIT ProfessionalAuthor Commented:
what about viewing the existing cluster heartbeat network threshold value ?

what command do I need to type and does that command can be executed on the production cluster node safely ?
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