Lync – B4Z.co.uk

I had a customer log a support case detailing an issue whereby all Lync 2010 clients were displaying a red banner stating “Limited functionality is available due to an outage”, however this customer had only a single front end server. This message is typically displayed when users registered against and SBA experience a WAN outage in their location which results in them being unable to contact the associated front end server. The message shown in the client is illustrated below.

This issue affected all users registered again the front end server and upon viewing the application, system and Lync Server event logs a picture of how the issue was produced could be gained. Firstly in the front end server Lync Server event log the following error had been produced at the time the customer reported the issue:

Pas with FQDN: lync.domain.co.uk has been detected to be down.

PAS stands for Presence Agent Server and is the component of the Lync Server handling presence logic and traffic, turning to the system event logs on the front end detailed why the problem had occurred and why contacts could not be seen within the Lync client. The first error displayed was the following:

Reset to device, \Device\RaidPort0, was issued.

This detailed that access to the virtual machines storage subsystem had been interrupted for a short period of time and as such the following event was then also displayed:

SQL Server has encountered 1 occurrence(s) of I/O requests taking longer than 15 seconds to complete on file [c:\csdata\backendstore\rtc\dynlogpath\rtcdyn.ldf] in database [rtcdyn] (7). The OS file handle is 0x0000000000000740. The offset of the latest long I/O is: 0x000000060aca00

The above error essentially caused the underlying message that was displayed in the Lync client and in order resolve the problem the virtual machine was moved to another virtualisation host which immediately caused the error in the client to disappear as reliable access to the storage volume was now possible.

I was recently deploying a Microsoft Lync Server 2013 Standard Edition pool pair for a customer that was geographically dispersed. During the implementation, which was a migration from Lync Server 2010, I experienced an issue when running step 2 of the deployment wizard following the application of front end resiliency via the Topology Builder. On running the deployment wizard the following error was produced on the front end that was not responsible for holding the CMS.

The “Exception of type Microsoft.Rtc.Management.Deployment.DeploymentException” was being thrown every time I tried to run the deployment wizard, and additionally I noted the file and master replication services has been set to disabled in the services MMC snap-in which further indicated the process had not completed correctly. On further investigation, the Lync Server application event log also produced the following error:

Microsoft Lync Server 2013, Backup Service central management backup module failed to register with back-end database. The module will continuously attempt to reconnect to the back-end. While this condition persists, no backup will be done.

The Connection string: Data Source = (local)\rtc;
Database = xds;
Max Pool Size = 3;
Connection Timeout = 60;
Connection Reset = false;
Enlist = false;
Integrated Security = true;
Pooling = true;
Exception: [2000] Cannot open database “xds” requested by the login. The login failed.
Login failed for user ‘NT AUTHORITY\NETWORK SERVICE’.
Cause: Possible issues with central management backup module back-end database.
Resolution: Ensure central management backup module back-end is functioning correctly.

On reviewing the error and confirming the backup service was started, in order to resolve the issue the following actions were performed.

1. In the Lync Topology Builder remove the front end resiliency settings that were previously applied and publish the topology.

2. Connect to each front end server that comprises the pool pairing and run step two of the deployment wizard, by performing this the replicator and backup services will be removed and essentially the pairing will be broken.

3. In the topology Builder re-apply the resiliency settings and publish the topology in order to recreate the pairing.

4. Connect to each front end server that comprises the pool pairing and run step two of the deployment wizard, by performing this the replicator and backup services will be added again. Once the deployment wizard is completed, ensure the backup services are started on each front end and ensure the Invoke-CSBackupServiceSync PowerShell commands are run as per the “What to do next” information.

5. In the Lync Server Mangement Shell run the “Get-CsBackupServiceStatus -PoolFqdn yourpool.domain.local” and ensure the services is operating in a normal state for both front end servers.

That’s it, the deployment wizard and associated xds database access error should now be cleared.