NonStop NS1200 Planning Guide

Fibre Channel port location and cable connections vary depending on the various controller and
Fibre Channel disk module combinations.
Configurations for Fibre Channel Devices
Each VIO enclosure in an Integrity NonStop NS1200 system contains four Fibre Channel ports
that support up to 16 Fibre Channel disk modules (FCDMs) in a daisy-chained configuration,
with identification of the FCDMs depending on the ServerNet connection to the Fibre Channel
ports on the VIO enclosure.
Configuration Restrictions for Fibre Channel Devices
These configuration restrictions apply and are invoked by Subsystem Control Facility (SCF):
• Primary and mirror disk drives in FCDMs cannot connect to the same Fibre Channel loop.
Loss of the Fibre Channel loop makes both the primary volume and the mirrored volume
inaccessible. This configuration inhibits fault tolerance.
• Disk drives in different FCDMs within a daisy-chain connect to the same Fibre Channel
loop.
• The primary path and backup Fibre Channel communication links to a disk drive should
not connect to Fibre Channel ports in the same VIO enclosure. Loss of one Fibre Channel
port can make multiple disk drives inaccessible on a single Fibre Channel communications
path. This configuration is allowed, but only if you override an SCF warning message.
• The mirror path and mirror backup Fibre Channel communication links to a disk drive
should not connect to Fibre Channel ports in the same VIO enclosure. Loss of one Fibre
Channel port can make multiple disk drives inaccessible on a single Fibre Channel
communications path. This configuration is allowed, but only if you override an SCF warning
message.
Recommendations for Fibre Channel Device Configuration
Different device types must be on different Fibre channel loops. For example, do not put disk
and tape devices on the same Fibre Channel loop.
These recommendations apply to VIO Fibre Channel ports and FCDM configurations:
• Primary FCDM connects to the VIO Fibre Channel port 1.
• Mirror FCDM connects to the VIO Fibre Channel port 2.
• FC-AL port A1 is the incoming port from a Fibre Channel port on the VIO enclosure or from
another FCDM.
• FC-AL port A2 is the outbound port to another FCDM.
• FC-AL port B2 is the incoming port from a Fibre Channel port on the VIO enclosure or from
a FCDM.
• FC-AL port B1 is the outbound port to another FCDM.
• In a daisy-chain configuration, the ID expander harness determines the enclosure number.
Enclosure 1 is always at the bottom of the chain.
• Fibre Channel ports are located in slot 1of a VIO enclosure.
54 System Configuration Guidelines