HP StorageWorks Data Replication Manager HSG80 ACS Version 8.7P Configuration Guide (AA-RPHZF-TE, March 2004)

Introduction to Data Replication Manager
20 Data Replication Manager HSG80 ACS Version 8.7P Configuration Guide
Data Replication Manager Overview
DRM provides a disaster-tolerant (DT) storage solution through the use of hardware
redundancy and data replication between two sites separated by some distance. Multiple
heterogeneous servers can be connected to one or more shared storage subsystems.
A basic DRM configuration consists of two sites—an initiator and a target. The initiator site
carries out primary data processing. The target site is used for data replication. As data
processing occurs at the initiator site, the data is replicated or mirrored to the target site. If a
single component at either site fails, DRM will fail over to a redundant component at the same
site to allow continued operation. For example, if one of the dual-redundant Fibre Channel
links between the sites were to fail, DRM would fail over to the other link. If a significant
failure (disaster) occurs at the initiator site, data processing can be resumed at the target site,
where the data is intact. This process is called site failover. When the cause of the initiator site
failover has been resolved, data processing can be moved back to the initiator site in a process
called site failback.
DRM uses the peer-to-peer remote copy function of the HSG80 controller to achieve data
replication. HSG80 controller pairs at the initiator site are connected to their partner HSG80
controller pairs at the target site. This process is completely host independent.
The connection between the two DRM sites is called an intersite link (ISL). There are two
ISLs for redundancy. An ISL can be one of several transport modes. For example, short
distances can use direct Fibre Channel links, but longer distances may require asynchronous
transport mode (ATM). For more detailed information on supported ISLs, refer to the HP
StorageWorks Continuous Access and Data Replication Manager SAN Extensions Reference
Guide and to the most recent DRM Release Notes for any support information related to your
operating system.
Heterogeneous Storage Area Networks
This section describes heterogeneous storage area networks (SANs) in a DRM environment.
Previous implementations of DRM required all operating systems in a DRM environment to
be the same (homogeneous). The latest version of the Array Controller Software (ACS)
supports a mixed (heterogeneous) environment of operating systems, making DRM much
more scalable and manageable in a customer data center.
SANs are becoming more complicated to manage and maintain. In today’s Information
Technology world, few businesses carry out their day-to-day operations within a single
operating system (OS) topology. Many businesses have a mixture of operating system
platforms carrying out different business functions. They may have electronic mail services
running on Windows 2000, critical business applications on UNIX, and file-print services on
NetWare. These may be running in several data centers on several different SANs. By using a
heterogeneous DRM SAN environment, they can be combined into a single SAN and use a
single implementation of DRM for business critical applications.
Refer to the HP StorageWorks SAN Design Reference Guide for more information on
designing and building heterogeneous SANs. If the HP StorageWorks SAN Design Reference
Guide contradicts this guide, consider this guide correct for DRM configurations only.