Exchange Server 2013 - File Share Witness.

Exchange Server 2013 - File Share Witness.

File Share Witness plays an important role in Exchange 2013 DAG. Without File Share Witness the DAG will not work in operational Mode. FSW will play their role when there is even number of DAG. The inner core cluster technology is implemented utilizing the quorum type Node and File Share Majority.

To check the File Share Witness Server use the following powershell command

Get-Cluster | Get-ClusterQuorum | FL

When the DAG member is in even number the witness.log file is locked by the cluster computer account which provides teh quorum type type Node and File Share Majority.

By default in the odd DAG members we will not able to see the witness.log file in the shared drive of file share witness server.

Hence the witness.log file will not get created. To check the Witness.log file when it get locked use the following command

C:\>net file

ID         Path                     User name            # Locks
----------------------------------------------------------------
1677722253 E:\fsw\Witness.log        ExAdmin$             0

When you have two File Share witness server as primary and alternate in DAG. Sometime we need to find which FSW Server the DAG is mapped. This can acheived using the below powershell command

Get-DatabaseAvailabilityGroup -Identity DAG -Status | Select-Object Name,Servers,WitnessServer,WitnessDirectory,AlternateWitnessServer,AlternateWitnessDirectory,OperationalServers,PrimaryActiveManager,WitnessShareInUse                          
On executing the above powershell command check the value WitnessShareInUse. It can hold the below value

Primary - means it uses primary file share witness server
Alternate - means it uses secondary file share witness server