Designing Disaster Tolerant High Availability Clusters, 10th Edition, March 2003 (B7660-90013)

Building a Continental Cluster
Switching to the Recovery Packages in Case of Disaster
Chapter 5 253
change in the remote cluster’s state. The following table shows the status
of ContinentalClusters packages after recovery has taken place, and
applications are now running on the local cluster.
How the cmrecovercl Command Works
The cmrecovercl command uses the configuration file to loop through
each defined recovery group. For each group, the command
communicates with the monitor package (ccmonpkg) and verifies that
the remote cluster is unreachable or down, then if there is a data
replication package it is halted, and the recovery package is enabled on
the Recovery Cluster. The recovery package can then start up on the
local cluster on the appropriate node, as determined by the
FAILOVER_POLICY configured for the package.
The process continues for the next recovery group, even if there are
problems with one recovery group. After processing one recovery group,
if the command discovers that the local cluster is back up, the command
exits, since the alarm or alert state no longer exists. This process keeps
both the primary and recovery packages from running on the remote
cluster and local cluster at the same time, which would result in data
corruption.
Table 5-6 Status of ContinentalClusters Packages After Recovery
Primary Cluster Recovery Cluster
Data
Replication
Method
Primary
Package
Data
Sender
Package
Optional
Monitor
Package
Recovery
Package
Data
Receiver
Package
Require
d
Monitor
Package
Physical—
Symmetrix
Halted Not used Halted or
Running
Running Not used Halted or
Running
Physical—
XP Series
Halted Not used Halted or
Running
Running Not used Halted or
Running
Logical—
Oracle
Standby
Database
Halted Not used Halted or
Running
Running Halted Halted or
Running