A clustered operating system is a collection of independent operating system images working together as one. The objective is to spread work around the cluster to achieve better load balancing, throughput, and availability.
Clustered applications appeared before their operating system counterpart. Application clusters operated over multiple processes within a single operating system image. Now clustered applications are enhanced to operate throughout an operating system cluster.
Adabas Cluster Services allows multiple instances of the Adabas server to operate against the same database across multiple operating system images, which enhances the general clustering approach for high-end systems.
A clustered application is a collection of independent jobs operating together as a single service.
Each implementation of a clustered application allows client sessions to migrate from one job to another across one or more images in an operating system cluster. The memory associated with a particular client session must be migrated along with the client session itself.
The following clustered applications may be implemented within a single operating system image:
CICS/MRO with dynamic transaction routing in z/OS and VSE/ESA
IMS TM in z/OS
UTM in BS2000
The following clustered applications are available for operating system clusters:
CICSplex in z/OS
IMSplex in z/OS
Adabas Cluster Services allows you to use multiple images of the Adabas
server across an operating system cluster in order to provide truly scalable
throughput. The cluster of Adabas servers can take part in distributed
transaction processing, under the control of Adabas Transaction Manager. This
is controlled by the ADARUN DTP parameter, in the same
way as for a standard Adabas nucleus. The same value must be specified for the
DTP parameter for every nucleus in the cluster.
Support for clustered applications within a single system image or across multiple system images in an operating system cluster is enabled by the Adabas System Coordinator when running one or more of the following Adabas add-on products:
Adabas Fastpath
Adabas Vista
Adabas Transaction Manager
Adabas SAF Security
Adabas Fastpath also uses the Adabas System Coordinator to host the Asynchronous Buffer Manager service.
When defining a job parameter for CICS/MRO with dynamic transaction routing or for CICSplex, select the job type CICS DTR.
CICS DTR jobs have user context information allocated from shared memory rather than from local (job) memory.
Refer to the Adabas System Coordinator documentation for more information.