Understanding the Db2 pureScale Feature resource model for AIX

The Db2 pureScale® Feature resource model represents cluster caching facilities, members and the shared cluster file system.

The Db2 pureScale Feature resource model differs from the other resource models used for the various automated HA deployments in Db2.

In the resource model for a Db2 pureScale instance, it is necessary to represent cluster caching facilities (CFs) and the shared clustered file system, along with the members. One of the CFs fulfills the primary role, which contains the currently active data for the shared data instance. The second CF maintains a copy of pertinent information for immediate recovery of the primary role.

Creating the associated resources for the cluster caching facilities allows IBM® Tivoli® System Automation for Multiplatforms (Tivoli SA MP) to appropriately automate the movement of the primary role in case of failure of the primary CF node.

Db2 cluster services includes three major components:
  • Cluster manager: Tivoli® SA MP, which includes Reliable Scalable Cluster Technology (RSCT)
  • Shared clustered file system: IBM Storage Scale
  • Db2 cluster administration: Db2 commands and administration views for managing and monitoring the cluster
Figure 1. Db2 Cluster services
Diagram shows how DB2 Cluster services interact with the primary and secondary servers

Db2 cluster services provide essential infrastructure for the shared data instance to be highly available and to provide automatic failover and restart as soon as the instance has been created.

Db2 cluster elements are representations of entities that are monitored and whose status changes are managed by Db2 cluster services. There are three types of Db2 cluster elements:
  • Hosts: A host can be a physical machine, LPAR (Logical Partition of a physical machine), or a virtual machine.
  • Db2 members: A Db2 member is the core processing engine and normally resides on its home host.
  • The home host of a Db2 member is the host name that was provided as the member's location when the member was added to the Db2 shared data instance. A Db2 member has single home host. Db2 members can accept client connections only when they are running on their home host.
  • Cluster caching facilities (CFs): The cluster caching facility (CF) is a software application managed by Db2 cluster services that provides internal operational services for a Db2 shared data instance. There is not necessarily a one-to-one mapping between Db2 cluster elements and the underlying cluster manager resources and resource groups.