HP Integrity Superdome SX2000 Cluster Installation and Configuration Guide - W - Page 13

Resource Dependencies, Services and Applications, Quorums, Disk Only

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and application fails over, the states of each resource are altered according to their dependencies on the other resources in the service and application. Resource Dependencies A dependency is a reliance between two resources that makes it necessary for both resources to run on the same node (for example, a Network Name resource depending on an IP address). The only dependency relationships that cluster service recognizes are relationships between resources. Cluster service cannot be told, for example, that a resource depends on a Windows Server 2008 service; the resource can only be dependent on a resource representing that service. Services and Applications Services and applications are managed as single units for configuration and recovery purposes. If a resource depends on another resource, both resources must be a member of the same service or application. For example, in a file share resource, the service or application containing the file share must also contain the disk resource and network resources (such as the IP address and NetBIOS name) to which clients connect to access the share. All resources within a service or application must be online on the same node in the cluster. NOTE: During failover, entire services and applications are moved from one node to another node in the cluster. A single resource cannot fail from one node to another. Quorums The Windows Server 2008 failover clustering quorum model is entirely new and represents a blend of the earlier shared disk and majority node set models. In Windows Server 2008 failover clustering there are now four ways to establish a quorum. The following is a list of the different quorum types and their characteristics: • Disk Only - This is the traditional MSCS quorum model, where a shared quorum disk must be online and nodes must be able to communicate with that disk. In this configuration, the disk is the master. The nodes have no votes, and the cluster stays up even when only one node can talk to the disk. Cluster Terminology 13

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and application fails over, the states of each resource are altered according to their dependencies
on the other resources in the service and application.
Resource Dependencies
A dependency is a reliance between two resources that makes it necessary for both resources to
run on the same node (for example, a Network Name resource depending on an IP address).
The only dependency relationships that cluster service recognizes are relationships between
resources. Cluster service cannot be told, for example, that a resource depends on a Windows
Server 2008 service; the resource can only be dependent on a resource representing that service.
Services and Applications
Services and applications are managed as single units for configuration and recovery purposes.
If a resource depends on another resource, both resources must be a member of the same service
or application. For example, in a file share resource, the service or application containing the file
share must also contain the disk resource and network resources (such as the IP address and
NetBIOS name) to which clients connect to access the share. All resources within a service or
application must be online on the same node in the cluster.
NOTE:
During failover, entire services and applications are moved from one node to another
node in the cluster. A single resource cannot fail from one node to another.
Quorums
The Windows Server 2008 failover clustering quorum model is entirely new and represents a
blend of the earlier shared disk and majority node set models. In Windows Server 2008 failover
clustering there are now four ways to establish a quorum.
The following is a list of the different quorum types and their characteristics:
•
Disk Only
– This is the traditional MSCS quorum model, where a shared quorum disk must
be online and nodes must be able to communicate with that disk. In this configuration, the
disk is the master. The nodes have no votes, and the cluster stays up even when only one
node can talk to the disk.
Cluster Terminology
13