using the SRDF facility. In the event of node failure, the integration of Metrocluster with EMC SRDF with the package will allow the application to fail over in the following ways:

•Among local host systems that are attached to the same EMC Symmetrix.

•Between one system that is attached locally to its EMC Symmetrix and another “remote” host that is attached locally to the other EMC Symmetrix.

Metrocluster with Symmetrix SRDF is specifically for configuring one or more Serviceguard packages whose data reside on EMC Symmetrix ICDAs (Integrated Cache Disk Arrays) and replicated with SRDF (Symmetrix Remote Data Facility).

Metrocluster with Symmetrix SRDF can be used in metropolitan cluster configuration. The distance between the two data centers is limited by the distance of the Symmetrix arrays physical connection requirements, and the distance of Serviceguard heartbeat round-trip time (0 < 200 ms), whichever is less. Symmetrix configurations can be either 1 by 1 (one Symmetrix at each data center) or M by N (one or two Symmetrix frames at each data center).

Configuration of Metrocluster with EMC SRDF must be done on all the cluster nodes, as is done for any other Serviceguard package. To use Metrocluster with EMC SRDF, Symmetrix host-based software for control and status of the EMC Symmetrix disk arrays must also be installed and configured on each HP 9000 and HP Integrity Servers host system that would execute the application package.

Overview of EMC and SRDF Concepts

EMC and Symmetrix Remote Data Facility (SRDF) is a Symmetrix-based business continuance and disaster recovery solution. SRDF is a configuration of Symmetrix systems, the purpose of which is to maintain multiple, real-time copies of logical volume data in more than one location. The Symmetrix systems can be in the same room, in different buildings within the same campus, or hundreds of kilometers apart.

By maintaining real-time copies of data in different physical locations, SRDF enables the following operations with minimal impact on normal business operations:

•Disaster Recovery

•Recovery from planned outages

•Remote backup

•Data center migration

•Data Replication and Mobility

Figure 39 EMC R1 and R2 Definitions

256 Building Disaster Recovery Serviceguard Solutions Using Metrocluster with EMC SRDF