Designing Disaster Recovery Clusters using Metroclusters and Continentalclusters, Reprinted October 2011 (5900-1881)

7 Designing a Disaster Recovery Solution Using Site Aware
Disaster Tolerant Architecture
This chapter describes Site Aware Disaster Tolerant Architecture (SADTA) for deploying complex
workloads with inter-dependent packages that are managed collectively for disaster tolerance in
Metrocluster. SAP and Oracle RAC database, which includes 10gR2 RAC, 11gR1 RAC, and
11gR2 RAC are some examples of complex workloads.
Special software features such as Site Controller Package, and Site Safety Latch, provide robust
automatic failover of the multi-instance workload between the two sites.
This chapter addresses the following topics:
• “Overview of Site Aware Disaster Tolerant Architecture” (page 337)
• “Configuring Complex Workloads using Site Aware Disaster Tolerant Architecture” (page 344)
• “Configuring Oracle RAC Database in a Site Aware Disaster Tolerant Architecture” (page 361)
• “Configuring Oracle RAC Database with ASM in a Site Aware Disaster Tolerant Architecture”
(page 383)
• “Understanding Failure Scenarios in a Site Aware Disaster Tolerant Architecture” (page 391)
• “Administering the Site Aware Disaster Tolerant Metrocluster Environment” (page 395)
• “Limitations of a Site Aware Disaster Tolerant Architecture” (page 405)
• “Troubleshooting” (page 405)
Overview of Site Aware Disaster Tolerant Architecture
SADTA enables deploying complex workloads in a Metrocluster. Complex workloads are
applications configured using multi-node and failover packages with dependencies. The packages,
henceforth referred to as complex-workload packages, are configured over isolated sub-clusters,
such as Oracle Clusterware, or Serviceguard Management Suite (SG SMS) Cluster File system,
which are created within the Metrocluster. Sub-clusters have access only to the storage arrays
within their respective sites. The Site Controller Package monitors the workload packages, and
collectively manages them all together. When the workload is no longer able to run on the current
site, the Site Controller Package performs a site failover and moves the workload to the other site.
The workload is moved to a site by starting the redundant package configuration for the workload
on that site. The Site Safety Latch mechanism ensures that at anytime only one of the redundant
configurations of a workload is running in the Metrocluster.
This feature is available with Metrocluster with Continuous Access EVA, Metrocluster with EMC
SRDF, and Metrocluster with Continuous Access for P9000 and XP. For more information on the
required software and supported versions, see the Disaster Tolerant Clusters Products Compatibility
Feature Matrix available at:
http://www.hp.com/go/hpux-serviceguard-docs.
Complex Workload Configuration
A complex workload is a multi-instance application that uses active resources across multiple nodes
in a cluster. These workloads are configured using multiple, inter-dependent multi-node packages
or failover packages, such as critical application packages that are dependent on CFS DG and
MP packages, in Serviceguard. These complex-workload packages need to be managed and
moved collectively for disaster tolerance.
For more information on configuring a complex workload, see “Complex Workload Redundant
Configuration” (page 340).
Overview of Site Aware Disaster Tolerant Architecture 337