Let me share one of the interesting conversations I had couple of days ago with one of my colleagues. This was regarding Quorum Drive in Failover Cluster(This was Windows Server 2008R2).
Let me tell you the story in short. ” She had a Question regarding Quorum(Q Drive typically) disappearing from Failover Cluster Manager. She also verified all the 3 Nodes(Remember this was a 3 Node Cluster) in the cluster and was not able to locate the Q Drive.
So, is this Normal in Failover Cluster?? The Answer is Absolutely Yes, this is perfectly normal for any Failover Cluster(Starting Win Server 2008) with Odd Number of Nodes. Quorum Drive is not mandatory anymore starting Win Server 2008. This might be really confusing for folks who are coming from Windows Server 2003! Yes, you heard it right..There is no need of having a dedicated Drive to act as Quorum. In this case our Cluster Quorum was configured as “Node Majority“. In Other Words, all the nodes will be participating in forming a Quorum and will be voting. If one Node dies, we still have 2 nodes Up and Running(so, we still have Majority of votes) and hence our cluster will be running without any issues. If 2 Nodes dies, majority of Nodes are down, at this point our cluster goes down. The basic idea is to avoid single point of failure!
Modes of Quorum starting Windows Server 2008:
Node Majority: Each node that is available can vote. The cluster functions only with majority of the votes. – For Odd Number of Nodes.
Node and Disk Majority: Each node + a Dedicated Drive(Typically Q) will be voting. – For Even Number of Nodes.
Node and File Share Majority: Each node + File Share Witness will be voting. ( Personally, I wouldn’t prefer this for any number of nodes)
No Majority(aka Disk only): This is what we used to have till Windows Server 2003, where a dedicated Disk will be acting as a Quorum.
Note: Leave the Quorum Config as is, chosen by windows by default when configuring the cluster. Windows is smart enough to choose appropriate Quorum configuration for your cluster. Change only if you are sure about what you are doing. Also, please note that Quorum configuration can be changed any time even after creating a cluster.
In My lab, I’ve a 2 Node Single Instance Cluster. So I’ve Node and Disk Majority as my Quorum. Please see below screenshots.
See Quorum Configuration as Node and Disk Majority. ( Just Ignore the warning above :D, my Node2 is turned off as of now, hence that warning!)
How to change the Quorum Configuration?
Right click on your Windows Cluster and choose More Actions as shown below.
Now, you can click Next and choose your Quorum Configuration type and proceed further.
Just want to remind again, Don’t change anything unless you understand completely what you are doing!!…