HP D5970A - NetServer - LCII Installation And User Manual page 86

Chapter 4
The Rack Storage/12FC supports four host ports and, depending on the
configuration of the Rack Storage/12FC, there may be from two to four host ports.
Each configured logical drive consumes a particular bus-target ID-LUN on the
host system. Multiple sets of disk drives are connected to the FCArray Controller
via its drive channels. There are four drive channels on the Rack Storage/12FC.
NOTE
This section presents only a brief introduction to RAID
Controller operation. For additional details, consult the
HP Rack Storage/12FC Installation Guide.
Presently, Hewlett-Packard's FCArray Assistant only supports two configuration
types:
Simplex mode - Simplex configurations use a single FCArray Controller
card in the HP Rack Storage/12FC chassis. When configuring the HP Rack
Storage/12FC for a Simplex configuration, only one of the HSSDC Fibre
Channel ports on the FCArray Controller card is required, Port 0 or Port 1.
This allows the Rack Storage/12FC to operate in a single host or cluster
configuration without any additional changes. See Figures 4-43 and 4-44.
Dual Active (duplex) mode - Dual Active (or Active/Active)
configurations use two FCArray Controller cards in the same HP Rack
Storage/12FC chassis.
In Dual Active mode, two identical FCArray Controller cards are
connected to the same hosts via the host ports, to the same drives via the
drive channels and to each other via a special hardware link for heartbeat
sensing. This forms a redundant controller system. The two controllers
work together handling data traffic and mirror the write data in the
corresponding host's cache memory. If one of the controllers fails or
otherwise becomes non-operational, the surviving controller takes over its
responsibilities with no loss of data.
When configuring the HP Rack Storage/12FC for a Dual Active configuration, all
four HSSDC Fibre Channel ports must be connected to a FC Hub. See Figures
4-43 and 4-44.
Initially Controller 0/Port 0 and Controller 1/Port 1 are active. If a controller
failover condition occurs, then Controller 0/Port 1 and Controller 1/Port 0 go
active and remain active only during the failover condition. When the condition is
cleared, Controller 0/Port 1 and Controller 1/Port 0 go inactive again.
When creating LUN mappings for Failover configurations, only specify LUN
mappings for LUNs on the initially active controllers, Controller 0/Port 0 and/or
80
Configuration