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Chapter 2 About Universal Replicator Operations 2-9
Hitachi Universal Replicator for IBM /OS User’s Guide
Each LDKC controls 255 CUs, however the number of CUs that can be used for
USP V program products is up to 255. Therefore, the maximum number of
volumes that can be used for USP V program products is 130,560 (65,280
volumes for an LDKC).
Remote Copy Connections
The remote copy connections are the physical paths used by the primary
storage systems to communicate with the secondary storage systems. Remote
copy connections enable communication between the primary and secondary
storage systems. The primary storage systems and secondary storage systems
are connected via fibre-channel interface cables. You must establish paths
from the primary to the secondary storage system, and also from the
secondary to the primary storage system. Up to eight paths can be established
in both of these directions.
When fibre-channel interface (optical multimode shortwave) connections are
used, two switches are required for distances greater than 0.5 km (1,640
feet), and distances up to 1.5 km (4,920 feet, 0.93 miles) are supported. If
the distance between the primary and secondary sites is greater than 1.5 km,
the optical single mode long wave interface connections are required. When
fibre-channel interface (single-mode long wave) connections are used, two
switches are required for distances greater than 10 km (6.2 miles), and
distances up to 30 km (18.6 miles) are supported.
See section
Setting up Remote Copy Connections for further information on
installing and configuring the FC remote copy connections.
The URz remote copy configuration between primary storage system and
secondary storage system has the following requirements:
URz supports 1-to-1 remote copy connection in one journal group pair. In
one journal group pair, one primary storage system can be connected to
only one secondary storage system. This configuration ensures the backup
data consistency of two or more volumes (e.g., large databases) within the
same storage system.
Note: Hitachi strongly recommends that you establish at least two independent
remote copy connections from the primary storage system to the secondary
storage system and vice versa to provide hardware redundancy for this critical
communications path.