Understanding and Designing Serviceguard Disaster Recovery Architectures

Figure 15 Root package in a complex workload
Site A Site B
SiteA_Application_package
SiteA_RAC_MNP
SiteA_SG_CFS_DG
SiteB_Application_package
SiteB_RAC_MNP
SiteB_SG_CFS_DG
Root Packages
SiteB_SG_CFS_MPSiteA_SG_CFS_MP
Site Controller Package
Site Controller package is the container package that starts and stops a given complex workload.
It also monitors the complex workload packages and also makes sure the replicated storage is in
read/write state when the complex workload packages start up. This package provides a single
interface to prepare the storage and start, or stop the entire complex workload.
Site Safety Latch
A site safety latch ensures that only one set of complex workload packages runs in the entire cluster.
In other words, it ensures that if the primary packages are running, the recovery packages are not
started up and if the recovery packages are running, the primary packages are not started up.
The site safety latch is implemented as an EMS resource dependency configured for the root-most
packages of a complex workload. In other words, the root-most packages in both the primary and
the recovery complex workloads are configured to have a dependency on an EMS resource that
is unique to a given Site Controller package.
Types of Configuration
SADTA can be classified into two, based on the environments for which it is configured:
• Metrocluster SADTA configuration
• Continentalclusters SADTA configuration
Metrocluster SADTA configuration
In a Metrocluster SADTA configuration, there are two sites configured in the cluster. The same site
can operate as a primary or a recovery site or both, depending on the complex workloads
configured in the Metrocluster. Each complex workload is managed by a different Site Controller
package, allowing each to be managed independently. Figure 16 (page 39) shows a similar
configuration with a Web Server.
38 Metrocluster and Continentalclusters