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

Table 18 Metrocluster Continuous Access EVA Template Files (continued)
DescriptionName
package. The Metrocluster Continuous Access EVA environment file is
generated automatically starting with version A.05.00.
A directory containing sample convenience shell scripts that must be
edited before using. These shell scripts may help to automate some
configuration tasks. These scripts are contributed, and not supported.
/opt/cmcluster/toolkit/SGCAEVA/
Samples
Metrocluster Continuous Access EVA software has to be installed on all nodes that will run a
Serviceguard package whose data is on an HP StorageWorks EVA and where the data is replicated
to a second EVA using the Continuous Access EVA facility. In the event of a node failure, the
integration of Metrocluster Continuous Access EVA with the package will allow the application to
fail over in the following ways:
• Among local host systems attached to the same EVA.
• Between one system that is attached locally to its EVA and another “remote” host that is
attached locally to the other EVA.
Configuration of Metrocluster Continuous Access EVA must be done on all the cluster nodes, as is
done for any other Serviceguard package. To use Metrocluster Continuous Access EVA, Command
View EVA and SMI-S EVA must also be installed and configured on the Management Server.
Overview of EVA and Continuous Access EVA Concepts
Continuous Access EVA provides remote data replication from primary EVA systems to remote EVA
systems. Continuous Access EVA uses the remote-copy function of the Hierarchical Storage
Virtualization (HSV) controller running the controller software (VCS or XCS) to achieve
host-independent data replication. This section describes some basic Continuous Access EVA
terminology, concepts, and features. The topics discussed are:
• Data Replication
• Copy Sets
• DR Groups
• Log Disk
• Managed Sets
• Failover
Metrocluster with EVA and Data Replication
The HSV controller pairs at the primary location are connected to their partner HSV controller pairs
at the alternate location. To configure storage for data replication, a source Vdisk is specified in
the primary storage system. The destination Vdisk is then created by the controller software at the
remote storage system. As data is written to the source Vdisk, it is mirrored to the destination Vdisk.
Applications continue to run while data replication goes on in the background over a separate
interconnect. When a storage system contains both source Vdisks and destination Vdisks, it is said
to be bidirectional. A given storage system can have a bi-directional data replication relationship
with only one other storage system, and an individual Vdisk can have a uni-directional replicating
relationship with only one other Vdisk. The remote copy feature is intended not only for disaster
recovery, but also to replicate data from one storage system or physical site to another storage
system or site. It also provides a method for performing a backup at either the source or destination
site.
212 Building Disaster Recovery Serviceguard Solutions Using Metrocluster with Continuous Access EVA