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

To prevent packages from being started at the wrong time and in the wrong place, use the following
strategies:
• Set the AUTO_RUN (PKG_SWITCHING_ENABLED used prior to Serviceguard
A.11.12) parameter for all primary and recovery packages to NO.
• Ensure that recovery package names are well known, and that personnel understand they
should never be started with a cmrunpkg or cmmodpkg command unless the cmrecovercl
command has been invoked first.
• If a cluster has no packages to run before recovery, then do not allow packages to be run on
that cluster with Serviceguard Manager.
Network Attributes
Another important difference between the packages configured in Continentalclusters and the
packages configured in a standard Serviceguard cluster is that the same or different subnets can
be used for primary cluster and recovery cluster configurations. In addition, the same or different
relocatable IP addresses can be used for the primary package and its corresponding recovery
package. The client application must be designed properly to connect to the appropriate IP address
following a recovery operation. For recovery groups with a rehearsal package configured, ensure
that the rehearsal package IP address is different from the recovery package IP address.
How Serviceguard commands work in a Continentalclusters
Continentalclusters packages are manipulated manually by the user via Serviceguard commands
and by cmcld automatically in the same way as any other packages.
In Continentalclusters the recovery package is not allowed to run at the same time as the primary,
data sender, or data receiver packages. To enforce this, several Serviceguard commands behave
in a slightly different manner when used in Continentalclusters.
Table 8 describes the Serviceguard commands whose behavior is different in Continentalclusters
environment. Specifically, when one of the commands listed in Table 8 attempts to start or enable
switching of a package, it first checks the status of the other packages in the recovery group. Based
on the status, the operation is either allowed or disallowed.
The checking is done based on the stable clusters' environment and the proper functioning of the
network communication. In the case when the network communication between clusters can not
be established or the cluster or package status can not be determined, it must be checked manually
to ensure that the operation to be performed on the target package will not have a conflict with
other packages configured in the same recovery group.
Table 8 Serviceguard and Continentalclusters Commands
How the commands work in ContinentalclustersHow the commands
work in Serviceguard
Commands
Will not start a recovery package if any of the primary, data receiver,
or data sender package in the same recovery group is running or
runs a packagecmrunpkg
enabled. Will not start recovery package if the recovery group is in
maintenance mode. Will not start a primary, data receiver, or data
sender package if the recovery package in the same recovery group is
running or enabled. Will not start a rehearsal package when the
recovery group is not in maintenance mode.
Will not enable switching on a recovery package if any of the primary,
data receiver, or data sender package in the same recovery group is
enable switching
attribute for a highly
available package
cmmodpkg -e
running or enabled. Will not enable switching for a recovery package
if the recovery group is in maintenance mode. Will not enable a primary,
data receiver, or data sender package if the recovery package in the
same recovery group is running or enabled. Will not enable switching
for a rehearsal package when the recovery group is not in maintenance
mode.
Understanding Continentalclusters Concepts 47