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

Overview of Deploying a Complex Workload in 3DC using SADTA
Site Aware Disaster Tolerant Architecture (SADTA) enables deploying complex workloads in a
cluster. Complex workloads are applications configured using multi-node and failover packages
with dependencies. This complex workload is a multi-instance application that uses active resources
across multiple nodes in a cluster. These workloads are configured using multiple, interdependent
multi-node packages or failover packages. These packages that comprise a complex workload
need to be managed and moved collectively for disaster recovery. SADTA includes crucial
components such as the Site Controller Package and the Site Safety Latch that manage the complex
workload configuration. The Site Controller Package is a special failover package that is created
using the dts/sc module. Each complex workload that is configured using SADTA must have a
corresponding Site Controller Package. The Site Safety Latch is an internal mechanism that is
created for each Site Controller Package. It is created automatically on all the cluster nodes when
the corresponding Site Controller Package configuration is applied in the cluster. The Site Safety
Latch prevents the inadvertent simultaneous startup of the workload configuration on both sites.
SADTA is extended to support 3DC configurations. This enables deploying complex workloads in
a 3DC solution. This solution specifies a method to configure and move complex workloads across
three data centers, while using P9000 or XP Continuous Access 3DC replication technology for
replicating data.
Figure 80 shows the package view of a complex workload configuration in a 3DC solution using
SADTA. It shows three sites - Site1, Site2 and Site3. A Metrocluster is configured with Site1 and
Site2 and an independent Serviceguard cluster is configured at Site3. Continentalclusters is
configured with the Metrocluster as the primary cluster and the independent Serviceguard cluster
at Site3 is configured as the recovery cluster. A Serviceguard cluster at Site 3 is configured with
only one site defined in the cluster configuration.
Figure 80 Package view for SADTA configuration in a 3DC solution
In the 3DC Solution, a complex workload is configured redundantly by configuring it at all sites.
A separate set of packages is used to configure complex workloads at each site. A Site Controller
Package is created in both, the primary cluster (Metrocluster between Site1 and Site2) and the
recovery cluster (Serviceguard cluster at Site3) to manage the complex workload. A recovery group
is configured in Continentalclusters with the Site Controller Package in the primary cluster as a
primary package and the Site Controller Package in the recovery cluster as a recovery package.
448 Designing a Three Data Center Disaster Recovery Solution