Table 18 Metrocluster Continuous Access EVA Template Files (continued)

Name

Description

 

package. The Metrocluster Continuous Access EVA environment file is

 

generated automatically starting with version A.05.00.

 

 

/opt/cmcluster/toolkit/SGCAEVA/

A directory containing sample convenience shell scripts that must be

Samples

edited before using. These shell scripts may help to automate some

 

configuration tasks. These scripts are contributed, and not supported.

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