Understanding and Designing Serviceguard Disaster Recovery Architectures

Site Controller support
A site controller package is a container package for multiple, interdependent set of packages. The
multiple, interdependent set of packages is known as a complex workload. A Continentalclusters
recovery group can have a site controller package as its primary and recovery package. This helps
in simplifying disaster recovery of a complex stack of applications.
Data Replication Storage Failover Preview
Data Replication Storage Failover Preview allows you to preview the preparation for the storage
of the data replication environment in a Metrocluster failover or Continentalclusters recovery. This
is done with the cmdrprev command, which also verifies the data replication environment that
might cause a Metrocluster failover or Continentalclusters recovery to fail.
General Requirements
You must consider the following when configuring Continentalclusters over a WAN:
• Inter-cluster connections are TCP/IP based.
• The physical connection is one or more leased lines managed by a common carrier. Common
carriers cannot guarantee the same reliability that a dedicated physical cable can. The distance
can delay the propagation of data from primary to the remote copy. This can cause data
currency issues. Using higher speed WAN connections to improve data replication performance
and reduce latency, can increase the cost.
• Operational issues, such as working with different personnel trained on different processes,
and conducting failover rehearsals, become more difficult if the nodes in the cluster are placed
further apart.
Benefits of Continentalclusters
The following are the benefits of Continentalclusters:
• Continentalclusters provides the ability to monitor a high availability cluster and fail over
mission critical applications to another cluster if the monitored cluster is unavailable.
• Continentalclusters supports mutual recovery, therefore different critical applications can run
on each cluster, with each cluster configured to recover the mission critical applications of the
other.
• You can virtually build data centers anywhere and still have the data centers provide disaster
recovery for each other. Continentalclusters uses multiple clusters, therefore theoretically there
is no limit to the distance between the clusters. The distance between the clusters is dictated
by the required rate of data replication to the remote site, level of data currency, and the
quality of networking links between the two data centers.
• In addition, inter-cluster communication can be implemented with either a WAN or LAN
topology. LAN support is advantageous when you have data centers in close proximity to
each other, but do not want the data centers configured into a single cluster. One example
may be when you already have two Serviceguard clusters close to each other and for business
reasons, you cannot merge these two clusters into a single cluster. If you are concerned with
one of the centers becoming unavailable, Continentalclusters can be added to provide disaster
recovery. Furthermore, Continentalclusters can be implemented with an existing Serviceguard
cluster architecture while both the clusters are running, and provide flexibility by supporting
disaster recovery failover between two clusters that are on the same subnet or on different
subnets.
• Besides selecting your own storage and data replication solution, you can also take advantage
of the following HP pre-integrated solutions:
◦ Storage subsystems implemented by Metrocluster are also pre-integrated with
Continentalclusters. Continentalclusters uses the same data replication integration module
Understanding Continentalclusters 35