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

Understanding Changes in Continentalclusters A.08.00
Continentalclusters version A.08.00 uses Secure Shell (SSH) for secure communication across all
nodes. The following additional components are used in Continentalclusters A.08.00:
• Continentalclusters User and Group
• Continentalclusters Configuration Package
Continentalclusters User and Group
Continentalclusters version A.08.00 uses Secure Shell (SSH) for all inter-cluster and node
communication. A special Continentalclusters user, conclusr and group, conclgrp are used
for all communication over SSH. This Continentalclusters user and the group are automatically
created when Continentalclusters version A.08.00 is installed on a node. This user account is
created in the node using useradd and groupadd commands. The cluster administrator must
specify a password for this user on all nodes in the primary and recovery clusters. When a node
is no longer part of Continentalclusters A.08.00 configuration, this user must be deleted from the
removed node.
Continentalclusters Configuration Package
Continentalclusters version A.08.00 stores configuration information in a special package on the
primary and recovery clusters. This package is named ccconfpkg and is automatically created
on the primary and recovery clusters when a Continentalclusters configuration file is applied using
the cmapplyconcl command. This package is deleted on all clusters when the Continentalclusters
configuration is removed using the cmdeleteconcl command.
CAUTION: This package is internally managed by Continentalclusters version A.08.00. It is not
required to run this package in the primary or recovery cluster for proper Continentalclusters
operation. This special package will be displayed with Serviceguard status commands, such as
cmviewcl. Cluster administrators must not attempt to modify, delete, start, or stop this package
using Serviceguard commands.
Preparing the Clusters
The steps for configuring the clusters, needed by Continentalclusters, are as follows:
• Set up and test data replication between the sites.
• Configure each cluster for Serviceguard operation.
Setting up and Testing Data Replication
Depending on which data replication method you choose, it can take a week or more to set up
and test a data replication method. If there is more than one recovery pair configured in
Continentalclusters, a separate data replication link is required to be set up for a different recovery
pair (one for each pair).
In the sample configuration, physical data replication is done through a hardware link between
disk arrays. Because this method is hardware based, there is hardware set up and configuration
that can take several days. Some logical replication methods, such as transaction processing
monitors (TPMs), need application changes that are more easily done during the original application
development.
Make sure that the data replication to the recovery site is functional. This would include setting up
the physical data replication links across the WAN and making sure that the data is replicated
between the shared disk arrays.
If the data replication software is separate from the application itself, then a separate Serviceguard
package should be created for it. Some kinds of logical data replication require that a data receiver
package be running on the recovery cluster at all times. If data sender and data receiver packages
54 Designing Continentalclusters