How Clustering Works

Shared Cluster Disk Array

A shared disk array is a collection of storage disks that is being accessed by the cluster. This could be SAN or SCSI RAIDs. Windows Clustering supports shared nothing disk arrays. Any one node can own a disk resource at any given time. All other nodes will not be allowed to access it until they own the resource (Ownership change occurs during failover). This protects the data from being overwritten when two computers have access to the same drives concurrently.

Quorum Drive

This is a logical drive assigned on the shared disk array specifically for Windows Clustering. Clustering services write constantly on this drive about the state of the cluster. Corruption or failure of this drive can fail the entire cluster setup.

Cluster Name

This name refers to Virtual Cluster Name, not the physical node names or the Virtual SQL Server names. It is assigned to the cluster as a whole.

Cluster IP Address

This IP address refers to the address which all external connections use to reach to the active cluster node.

Cluster Administrator Account

This account must be configured at the domain level, with administrator privileges on all nodes within the cluster group. This account is used to administer the failover cluster.

Cluster Resource Types

This includes any services, software, or hardware that can be configured within a cluster. Ex: DHCP, File Share, Generic Application, Generic Service, Internet Protocol, Network Name, Physical Disk, Print Spooler, and WINS.

Cluster Group

Conceptually, a cluster group is a collection of logically grouped cluster resources. It may contain cluster-aware application services, such as SQL Server 2000.

SQL Server Network Name (Virtual Name)

This is the SQL Server Instance name that all client applications will use to connect to the SQL Server.

SQL Server IP Address (Virtual IP Address)

This refers to the TCP/IP address that all client applications will use to connect to SQL Server; the Virtual Server IP address.

SQL Server 2000 Full-text

Each SQL Virtual Server has one full-text resource.

Microsoft Distributed Transaction Coordinator (MS DTC)

Certain SQL Server Components require MS DTC to be up and running. MS DTC is shared for all named / default instances in cluster group.

SQL Server Virtual Server Administrator Account

This is the SQL Server service account, and it must follow all the rules that apply to SQL Service user accounts in a non-clustered environment.

Copyright 2004 by the author. Published with the express permission of the author.