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Clusters: Configuration: Singleton Services

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This page lists the singleton services that are configured to migrate automatically within this cluster. You can use this page to add or remove singleton services from a cluster.

Automatic service migration allows the automatic health monitoring and migration of singleton services. A singleton service is a service operating within a cluster that is available on only one server at any given time. When a migratable service fails or become unavailable for any reason it is deactivated at its current location and activated on a new server.

If the migration of a singleton service fails on every candidate server within the cluster, the service is left deactivated. You can configure the number of times the number of times the migration master will iterate through the servers in the cluster.

Column Display

You can show fewer or additional data points on this page by expanding Customize this table and modifying the Column Display list. Each data point displays in its own table column.

The following table lists all of the data points that you can display in columns on this page.

Name Description
Name of

Name of singleton service.

MBean Attribute:
SingletonServiceMBean.Name

Changes take effect after you redeploy the module or restart the server.

Class Name

The fully qualified name of a class to load and run. The class must be on the server's classpath.

For example, mycompany.mypackage.myclass

MBean Attribute:
SingletonServiceMBean.ClassName

Changes take effect after you redeploy the module or restart the server.

Cluster Name

Returns the cluster this singleton service is associated with.

MBean Attribute:
SingletonServiceMBean.Cluster

Changes take effect after you redeploy the module or restart the server.

Hosting Server

Returns the name of the server that currently hosts the singleton service.

MBean Attribute:
SingletonServiceMBean.HostingServer

Preferred Server

Returns the server that the user prefers the singleton service to be active on.

MBean Attribute:
SingletonServiceMBean.UserPreferredServer

Candidate Servers

Return a list of servers that are candiates to host the services deployed to this migratable target. If the ConstrainedCandidateServer list is empty, all servers in the cluster are returned. If the ConstrainedCandidateServer is not empty those servers only will be returned. The user preferred server will be the first element in the list returned.

MBean Attribute:
SingletonServiceMBean.AllCandidateServers

Constrained Candidate Servers

Returns the (user restricted) list of servers that may host the migratable target. The target will not be allowed to migrate to a server that is not in the returned list of servers. This feature is used to e.g. configure the two server that have acceess to a dual ported disk. All servers in this list must be part of the cluster that is associated with the migratable target.

MBean Attribute:
SingletonServiceMBean.ConstrainedCandidateServers

Changes take effect after you redeploy the module or restart the server.

Related Tasks

Related Topics