Compaq StorageWorks Data Replication Manager HSG80 ACS Version 8.5P Operations Guide

1–2 Compaq StorageWorks Data Replication Manager HSG80 ACS Version 8.5P Operations Guide
The DRM sites are connected over some distance via fiber optic cable or ATM. Data
Replication Manager uses Fibre Channel gigabit switches to send the data between the
sites. Other hardware may be inserted between the fibre channel switches if longer
distances exist between sites.
Peer-to-Peer Remote Copy Function
Data Replication Manager 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. Remote copy sets are
created from units at the initiator and target sites. These remote copy sets are mirrors of
each other. As data is written to a unit at the initiator, it is mirrored to its remote copy set
partner unit at the target site.
The HSG80 controllers provide failover and failback capabilities in case of failures.
Failover makes the data available at the target site after a failure. Failback is used to move
data operations back to the initiator once it has been brought back on-line.
Hardware Redundancy
Data Replication Manager provides hardware redundancy. In the face of single component
failures at a site, Data Replication Manager will failover to a redundant component at that
site to allow continued operations. For example, if one of the dual-redundant Fibre
Channel links between the sites were to fail, Data Replication Manager would switch to
the other link.
Hardware Components
Data Replication Manager uses a minimum of two HSG80 array controller pairs: one at
the initiator site and one at the target site. Each site houses one or more ESA12000
cabinets that are equipped with one or more BA370 enclosures and disk Storage Building
Blocks (SBBs). Each BA370 enclosure holds 24 disks.
NOTE: Data Replication Manager can run with cabinets that have 24, 48, or 72 (requires two
cabinets) disk drives, but the initiator and target sites must be equipped with the identical
number of disks.
The hosts at the initiator and target sites are connected to a pair of dual redundant HSG80
array controllers, which are located inside of these enclosures. See the RA8000 and
ESA12000 Storage Subsystems User’s Guide for complete details on this equipment.