Windows Cluster Interview Questionsand Answers

Here are some windows cluster Interview Questionsand Answers for windows administrator

What is Clustering? Briefly define & explain it?

 Clustering is a technology, which is used to provide High Availability for mission critical applications. We canconfigure cluster by installing MCS (Microsoft cluster service) component from Add remove programs, which can onlyavailable in Enterprise Edition and Data center edition.

Types of Clusters?

 In Windows we can configure two types of clusters

1. NLB

 (network load balancing) cluster for balancing load between servers. This cluster will not provide any highavailability. Usually preferable at edge servers like web or proxy.

2. Server Cluster:

 This provides High availability by configuring active-active or active-passive cluster. In 2 nodeactive-passive cluster one node will be active and one node will be stand by. When active server fails the applicationwill FAILOVER to stand by server automatically. When the original server backs we need to FAILBACK theapplication

What is Quorum ?

 A shared storage need to provide for all servers which keeps information about clusteredapplication and session state and is useful in FAILOVER situation. This is very important if Quorum disk fails entirecluster will fails.

Why Quorum is necessary ?

 When network problems occur, they can interfere with communication between cluster nodes. A small set of nodesmight be able to communicate together across a functioning part of a network, but might not be able to communicate

with a different set of nodes in another part of the network. This can cause serious issues. In this “split” situation, at

least one of the sets of nodes must stop running as a cluster.To prevent the issues that are caused by a split in the cluster, the cluster software requires that any set of nodesrunning as a cluster must use a voting algorithm to determine whether, at a given time, that set has quorum. Becausea given cluster has a specific set of nodes and a specific quorum configuration, the cluster will know how many

“votes” constitutes a majority (that is, a quorum). If the number drops below the majority, the cluster stops running.

Nodes will still listen for the presence of other nodes, in case another node appears again on the network, but thenodes will not begin to function as a cluster until the quorum exists again.

For example, in a five node cluster that is using a node majority, consider what happens if nodes 1, 2, and 3 cancommunicate with each other but not with nodes 4 and 5. Nodes 1, 2, and 3 constitute a majority, and they continuerunning as a cluster. Nodes 4 and 5 are a minority and stop running as a cluster, which prevents the problems of a

“split” situation. If node 3 loses communication with othe

r nodes, all nodes stop running as a cluster. However, allfunctioning nodes will continue to listen for communication, so that when the network begins working again, thecluster can form and begin to run.

Different types of Quorum in Windows server 2008 ?

 1.Node Majority

 –

 Used when Odd number of nodes are in cluster.2.Node and Disk Majority

 –

 Even number of nodes(but not a multi-site cluster)3.Node and File Share Majority

 –

 Even number of nodes, multi-site cluster4.Node and File Share Majority

 –

 Even number of nodes, no shared storage

Different types of Quorum in Windows server 2003?

Standard Quorum :

 As mentioned above, a quorum is simply a configuration database for MSCS, and is stored inthe quorum log file. A standard quorum uses a quorum log file that is located on a disk hosted on a shared storageinterconnect that is accessible by all members of the cluster.Standard quorums are available in Windows NT 4.0 Enterprise Edition, Windows 2000 Advanced Server, Windows2000 Datacenter Server, Windows Server 2003 Enterprise Edition and Windows Server 2003 Datacenter Edition.

Majority Node Set Quorums:

 A majority node set (MNS) quorum is a single quorum resource from a server clusterperspective. However, the data is actually stored by default on the system disk of each member of the cluster. TheMNS resource takes care to ensure that the cluster configuration data stored on the MNS is kept consistent acrossthe different disks.Majority node set quorums are available in Windows Server 2003 Enterprise Edition, and Windows Server 2003Datacenter Edition.

Explain about each Quorum type?

 Node Majority: Each node that is available and in communication can vote. The cluster functions only with a majorityof the votes, that is, more than half.Node and Disk Majori

ty: 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.Node and File Share Majority: Eac

h node plus a designated file share created by the administrator (the “file sharewitness”) can vote, whenever they are available and in communication. The cluster functions only with a majority of

the votes, that is, more than half.

No Majority: Disk Only: The cluster has quorum if one node is available and in communication with a specific disk inthe cluster storage.

 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 asynchronized 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 clusterproperties 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 thetype of quorum resources in use. A geographic cluster can use either a shared disk or MNS quorum resource, whilean 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 fora standard cluster (for example, there must be on the Microsoft Cluster HCL). However, some situations that use anMNS cluster may have unique requirements (such as geographic clusters), where data must be replicated in real timebetween 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 ashared disk (for example SQL Server 2000), so while you do not need shared disks for the quorum, you do needshared 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.