How to make Two node Failover Clusters -Windows Server 2008 R2 (File share witness and disk majority )
What is clustering Definition ?
A failover cluster is a group of independent computers that work together to increase the availability of applications and services. The clustered servers (called nodes) are connected by physical cables and by software. If one of the cluster nodes fails, another node begins to provide service (a process known as failover). Users experience a minimum of disruptions in service.
· Four quorum modes.
failover clustering now supports four quorum modes. To provide maximum availability, the cluster can automatically adjust the quorum mode as nodes are added or removed from the cluster. The four quorum modes are:
1. Node Majority. Each node that is available and in communication can vote. The cluster functions only with a majority of the votes, that is, more than half. This is similar to Majority Node Set (MNS) in Windows Server 2003. This selection would be preferred with an odd number of nodes and if no shared disk/storage is provided.
2. Node and Disk Majority. Each node plus a designated disk in the cluster storage (the “disk witness”) can vote whenever they are available and in communication. The cluster functions only with a majority of the votes, that is, more than half. This is the recommended configuration with an even number of nodes and for when shared storage is available.
3. Node and File Share Majority. Each node plus a designated file share created by the administrator (the “file share witness”) can vote whenever they are available and in communication. The cluster functions only with a majority of the votes, that is, more than half. This would commonly be implemented in a geographically dispersed failover cluster environment.
4. No Majority: Disk Only. The cluster has quorum if one node is available and in communication with a specific disk in the cluster storage. Only the nodes that are also in communication with that disk can join the cluster. This is equivalent to the quorum disk in Windows Server 2003. The disk is a single point of failure, so only select scenarios should implement this quorum mode.
Which editions include failover clustering?
The failover cluster feature is available in Windows Server 2008 R2 Enterprise and Windows Server 2008 R2 Datacenter. The feature is not available in Windows Web Server 2008 R2 or Windows Server 2008 R2 Standard
prepare a cluster to host SQL 2008R2 (we will be installing in another post )
Using File share witness
Rename the network connectivity on both nodes
Next go to advanced settings
Change the priority of the cluster network card so that the domain network comes first
Next step we install Microsoft failover cluster features
We create the cluster with only one node at the beginning
Yes we need this cluster to be supported so we must run all the needed tests
set the cluster IP (note this is not the SQL or the application IP usually the failover application cluster set its own IP and name so we use the below ip addresses for managing the cluster )
we go to cluster more actions and configure quorum
we will use a file share witness
in the settings for this we will need to add only the cluster object but I found that adding the nodes also help in rare cases
we verify that everything green
We add the second node
Follow the defaults until finish
The final step to configure the needed networks this is optional configuration that we block the clients connections from this network
this is optional because the IP address is not registered in the DNS or reachable from the clients
Using node and Disk majority
(the disk numbers + the node numbers = must be odd number )
I am using the wizard in creating this cluster you can use the same method as above I have seen the wizard select 100G as quorum disk so to avoid anything that may go wrong I recommend that you use the above method but for the demonstration purpose I will follow the wizard in this demo .
we follow the same network configurations as above
We add the needed server to our cluster
We run the validation test
Now the results
We can safely ignore both the errors
as you can see its super easy to create .
This Post is the steps taken from Microsoft TechNet but with rearranging the topics to seem a bit logical for someone that does not know the technology (there is no point in reinventing the wheel). I also added my personal experience into it .
The soul purposes of this guide is to give some idea about the technology .you can use it to deploy your own Solution but I don’t recommended it as every infrastructure is a bit different than the other . Please remember the golden rules “60% planning 30% deployment 10% maintenance “. this rule saved me a lot of pain and grief .