With the high availability (HA) feature of IBM® DB2® 9.7, a DBA can set up redundant systems and a failover mechanism, thereby improving the availability of the database. A two-node shared disk HA topology contains an active node to host the DB2 instance and data, and a possive node, where the DB2 resources move in the event of failure. In this article, the authors present and work through two examples showing how to use db2haicu to configure high availability with a shared disk topology.
- Overview of HA concepts
- Setting up an automated HA topologyu for an instance with no databases
- Setting up an automated HA topology with pre-existing databases
- Post configuration testing
- Other configurations
- Problem determination
This article describes a distinct configuration of an automated DB2 for Linux® and UNIX® software failover solution that uses shared disk storage. The configuration is based on the DB2 high availability (HA) feature and the DB2 High Availability Instance Configuration Utility (db2haicu) available with the DB2 Version 9.7 software release.
With the High Availability (HA) feature of DB2 9.7, a database administrator (DBA) can set up redundant systems and a failover mechanism, thereby improving the availability of the database solution. In the event of an unplanned or planned outage, the instance fails over to the available redundant systems. The db2haicu tool can be used to configure such an HA system. During the db2haicu configuration process, the necessary HA resources and their relationships are defined to the cluster manager. Failure events in the HA system can then be detected automatically, and takeover operations can be run without manual intervention.
A two-node shared disk HA topology contains an active node to host the DB2 instance and data, and a passive node to which DB2 resources move in case of a failure event. For this topology, the two nodes are connected to each other over a single public network and wired to a shared disk storage system. The term shared storage describes a system in which one or more disks are cabled and defined to both the active and passive nodes but only mounted at one node at a time, that is, the node that hosts the active DB2 instance. At any given time, only one node has exclusive access to the shared storage disks. That is, only one node can effectively do input/output (I/O) to shared storage disks.
This article presents two primary examples. In the first example, we use the db2haicu interactive mode to automate a single network shared disk HA topology with no pre-existing databases. This example demonstrates how the creation of database objects add mount point resources to the cluster, and conversely, how the removal of databases objects remove mount point resources from the cluster.
In the second example, we configure a single network HA topology, automated using the db2haicu XML mode for DB2 instance with pre-existing databases. This shows how db2haicu can automatically discover mount points for pre-existing databases and create the appropriate cluster resources.
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Steve Raspudic has worked in the IBM Toronto Lab for over ten years, and has held numerous roles throughout the development, consulting, and service organizations. His recent interests are DB2 HA, DB2 HADR, and other HA technologies for DB2. Most recently, he drove the integration of HA clustering into the core DB2 engine and is currently the manager of the DB2 High Availability team at the Toronto Lab.
Selvaprabhu Arumuggharaj is an Advisory Software Engineer. He has worked for IBM for nine years supporting Information Management products including DB2 and Informix database engines. He currently works on DB2 Down Systems and Diagnostics (DSD) team supporting all DB2 customers, covering all engine components, and providing proactive support direction. He has solid knowledge of DB2 DPF and High Availability (HA) features and co-authored High Availability and Disaster Recovery Options for DB2 on Linux, UNIX, and Windows Redbooks® publication in 2008.