Frequently Asked Questions (Server Clusters: Quorum Options - Windows Server 2003)
Applies To: Windows Server 2003, Windows Server 2003 R2, Windows Server 2003 with SP1, Windows Server 2003 with SP2
What is a Majority Node Set cluster?
It is a cluster that has a quorum based on local disks in each node, rather than a shared disk.
How is the quorum information located on the system disk of each node kept in synch?
The server cluster infrastructure ensures that all changes are replicated and updated on all members in a cluster.
Can this method be used to replicate application data as well?
No, that is not possible in this version of clustering. Only Quorum information is replicated and maintained in a synchronized state by the clustering infrastructure.
Can I convert a standard cluster to an MNS cluster?
Yes. You can use Cluster Administrator to create a new Majority Node Set resource and then, on the cluster properties sheet Quorum tab, change the quorum to that Majority Node Set resource.
What is the difference between a geographically dispersed cluster and an MNS cluster?
A geographic cluster refers to a cluster that has nodes in multiple locations, while an MNS-based cluster refers to the type of quorum resources in use. A geographic cluster can use either a shared disk or MNS quorum resource, while an MNS-based cluster can be located in a single site, or span multiple sites.
What is the maximum number of nodes in an MNS cluster?
Windows Server 2003 supports 8-node clusters for both Enterprise Edition and Datacenter Edition.
Do I need special hardware to use an MNS cluster?
There is nothing inherent in the MNS architecture that requires any special hardware, other than what is required for a standard cluster (for example, there must be on the Microsoft Cluster HCL). However, some situations that use an MNS cluster may have unique requirements (such as geographic clusters), where data must be replicated in real time between sites.
Does a cluster aware application need to be rewritten to support MNS?
No, using an MNS quorum requires no change to the application. However, some cluster aware applications expect a shared disk (for example SQL Server 2000), so while you do not need shared disks for the quorum, you do need shared disks for the application.
Does MNS get rid of the need for shared disks?
It depends on the application. For example, clustered SQL Server 2000 requires shared disk for data. Remember, MNS only removes the need for a shared disk quorum.
If I have a 2-node MNS cluster, and lose one server, will the cluster continue to function?
No, in order to keep an MNS cluster running, it must have a majority of nodes online, i.e. (<Number of nodes configured in the cluster>/2) + 1. The following table shows the various combinations of configured nodes and node failures:
How do I back up and restore an MNS cluster?
There is a separate white paper on backing up and restoring clustered configurations. It will be published at the same location as this paper.
Is there a way I can allow for a “minority set” to take control of the cluster?
Yes, there is a way for a “minority” set to be allowed to start up and initialize the cluster. But this is a manual process and has to be done in a specified manner. Details on the same are available in “help”.
What happens if majority count is lost?
The cluster service will gracefully shutdown the cluster and all resources. Clients will lose connectivity and access to any of the clustered services. This is done to prevent the “split-brain” scenario.
Are there any limitations with regard to network latency and topography in an MNS cluster?
Requirements are the same as that for vanilla clusters. With regard to topography, we envisage the MNS feature to be predominantly used in geographically dispersed clustering scenarios. This normally means specific semantic requirements in terms of storage usable and management. OEMs provide prescriptive guidance on the same and customers should carefully read the same.
For the latest information about Windows Server 2003, see the Windows Server 2003 Web site at http://www.microsoft.com/windowsserver2003.
It is a cluster that has a quorum based on local disks in each node, rather than a shared disk.
How is the quorum information located on the system disk of each node kept in synch?
The server cluster infrastructure ensures that all changes are replicated and updated on all members in a cluster.
Can this method be used to replicate application data as well?
No, that is not possible in this version of clustering. Only Quorum information is replicated and maintained in a synchronized state by the clustering infrastructure.
Can I convert a standard cluster to an MNS cluster?
Yes. You can use Cluster Administrator to create a new Majority Node Set resource and then, on the cluster properties sheet Quorum tab, change the quorum to that Majority Node Set resource.
What is the difference between a geographically dispersed cluster and an MNS cluster?
A geographic cluster refers to a cluster that has nodes in multiple locations, while an MNS-based cluster refers to the type of quorum resources in use. A geographic cluster can use either a shared disk or MNS quorum resource, while an MNS-based cluster can be located in a single site, or span multiple sites.
What is the maximum number of nodes in an MNS cluster?
Windows Server 2003 supports 8-node clusters for both Enterprise Edition and Datacenter Edition.
Do I need special hardware to use an MNS cluster?
There is nothing inherent in the MNS architecture that requires any special hardware, other than what is required for a standard cluster (for example, there must be on the Microsoft Cluster HCL). However, some situations that use an MNS cluster may have unique requirements (such as geographic clusters), where data must be replicated in real time between sites.
Does a cluster aware application need to be rewritten to support MNS?
No, using an MNS quorum requires no change to the application. However, some cluster aware applications expect a shared disk (for example SQL Server 2000), so while you do not need shared disks for the quorum, you do need shared disks for the application.
Does MNS get rid of the need for shared disks?
It depends on the application. For example, clustered SQL Server 2000 requires shared disk for data. Remember, MNS only removes the need for a shared disk quorum.
If I have a 2-node MNS cluster, and lose one server, will the cluster continue to function?
No, in order to keep an MNS cluster running, it must have a majority of nodes online, i.e. (<Number of nodes configured in the cluster>/2) + 1. The following table shows the various combinations of configured nodes and node failures:
| Number of nodes configured in the cluster | Number of node failures |
|---|---|
|
1 |
0 |
|
2 |
0 |
|
3 |
1 |
|
4 |
1 |
|
5 |
2 |
|
6 |
2 |
|
7 |
3 |
|
8 |
3 |
There is a separate white paper on backing up and restoring clustered configurations. It will be published at the same location as this paper.
Is there a way I can allow for a “minority set” to take control of the cluster?
Yes, there is a way for a “minority” set to be allowed to start up and initialize the cluster. But this is a manual process and has to be done in a specified manner. Details on the same are available in “help”.
What happens if majority count is lost?
The cluster service will gracefully shutdown the cluster and all resources. Clients will lose connectivity and access to any of the clustered services. This is done to prevent the “split-brain” scenario.
Are there any limitations with regard to network latency and topography in an MNS cluster?
Requirements are the same as that for vanilla clusters. With regard to topography, we envisage the MNS feature to be predominantly used in geographically dispersed clustering scenarios. This normally means specific semantic requirements in terms of storage usable and management. OEMs provide prescriptive guidance on the same and customers should carefully read the same.
For the latest information about Windows Server 2003, see the Windows Server 2003 Web site at http://www.microsoft.com/windowsserver2003.
