Computer readable storage medium for migratable services

Abstract

A migration framework provides for the migration of services in a cluster. A migratable target contains a list of servers in the cluster capable of hosting a migratable service. A migration manager can migrate the service between servers in the migratable target, and can activate an instance of the service on the selected host server. The migration manager ensures that only one active instance of the service exists in the cluster. A service stub can serve a user request on servers in the migration target, such as by order of preference, until the user request is served on the server hosting the active instance. A lease manager can assign a lease period to determine how long a server hosts an active instance.

1 . A computer readable storage medium, with instructions stored thereon for automatically migrating a service in a server cluster, comprising: 
 deactivating an active service class instance located on a server in the server cluster;    selecting a new host server in the server cluster to host the active service class instance using a consensus subsystem, the new host server being selected from a migratable target containing a list of all servers in the server cluster capable of hosting an active instance;    activating the service class instance on the new host server; and    wherein the step of selecting a new host server further comprises selecting a new host server from the migratable target by selecting the next server in the list, the list of the migration target being ordered by preference, and determining whether a majority of servers in the migration target list agree on the selection.    
     
     
         2 . A computer readable storage medium, with instructions stored thereon for automatically migrating a service in a server cluster, comprising: 
 deactivating an active service class instance located on a server in the server cluster;    selecting a new host server in the server cluster to host the active service class instance using a consensus subsystem, the new host server being selected from a migratable target containing a list of all servers in the server cluster capable of hosting an active instance;    activating the service class instance on the new host server; and    further comprising:    assigning a lease to the server hosting the active service class instance, the lease containing the length of time for which the server can host the instance.    
     
     
         3 . A computer readable storage medium according to  claim 1 , further comprising: 
 renewing the lease on the server hosting the active service class instance.    
     
     
         4 . A computer readable storage medium according to  claim 1 , further comprising: 
 deactivating the active service class instance when the lease expires.