Fibre Channel
Fibre Channel is a high-performance ANSI standard network and storage interconnect for PCI-based Alpha systems. It is a full-duplex serial interconnect and can simultaneously transmit and receive over 100 megabytes per second. Fibre Channel supports simultaneous access of SCSI storage by multiple nodes connected to a Fibre Channel switch. A second type of interconnect is needed for node-to-node communications.
Features
- High-speed transmission, 2 Gb/s, 4 Gb/s, 8 Gb/s (depending on adapter). It is a full-duplex
serial interconnect that can simultaneously transmit and receive over 100 MB/s.
- Scalable configuration to support department to enterprise configurations.
- Long-distance interconnects: Fibre Channel supports multi mode fiber at 500 meters per link. Fibre Channel supports longer-distance interswitch links (ISLs) — up to 100 kilometers per link, using single-mode fiber and up to 600 kilometers per link with FC/ATM links. In addition, SANworks Data Replication Manager (DRM) configurations provide long distance ISLs through the use of the Open Systems Gateway and Wave Division Multiplexors.
- High availability: multipath support is available to provide configurations with no single point of failure.
Fibre Channel technology supports simultaneous use of these transport protocols:
OpenVMS Support
The following Fibre Channel features are supported by OpenVMS:
| Feature | OpenVMS Support |
|---|---|
| High-speed transmission | OpenVMS supports 2 Gb/s, full-duplex, serial interconnect (can simultaneously transmit and receive 200 MB of data per second). |
| Choice of media | OpenVMS supports fiber-optic media. |
| Long interconnect distances | OpenVMS supports multimode fiber-optic media at 500 meters per link and single-mode fiber-optic media (for interswitch links, ISLs) for distances up to 100 kilometers per link. |
| Multiple protocols | OpenVMS supports SCSI–3. Possible future support for IP. |
| Numerous topologies | OpenVMS supports switched FC (highly scalable, multiple concurrent communications) and multiple switches (fabric). Support is planned for arbitrated loop on the StorageWorks Modular Storage Array (MSA) 1000 storage system, only. |
The following Fibre Channel enterprise storage arrays are supported by OpenVMS:
- HSG60 - Fibre Channel based StorageWorks controller that supports up to two UltraSCSI wide single-ended device ports and two host ports.
- HSG80 - Fibre Channel based StorageWorks controller that supports up to six UltraSCSI wide single-ended device ports and two host ports
The following Fibre Channel storage systems are supported by OpenVMS:
- P2000 G3 FC
Addresses, WWIDs and Device Names
Fibre Channel devices for disk and tape storage come with factory-assigned worldwide IDs (WWIDs). These WWIDs are used by the system for automatic FC address assignment. The FC WWIDs and addresses also provide the means for the system manager to identify and locate devices in the FC configuration. The FC WWIDs and addresses are displayed, for example, by the Alpha console and by the HSG or HSV console.
In most situations, Fibre Channel devices are configured to have temporary addresses. The device's address is assigned automatically each time the interconnect initializes. The device may receive a new address each time a Fibre Channel is reconfigured and reinitialized. This is done so that Fibre Channel devices do not require the use of address jumpers. There is one Fibre Channel address per port.
In order to provide more permanent identification, each port on each device has a WWID, which is assigned at the factory. Every Fibre Channel WWID is unique. Fibre Channel also has node WWIDs to identify multiported devices. WWIDs are used by the system to detect and recover from automatic address changes. They are useful to system managers for identifying and locating physical devices.
OpenVMS names for Fibre Channel devices take the form FGx0, where:
- FG represents Fibre Channel
- x represents the unit letter, A to Z
- 0 is a constant
Examples of OpenVMS names for Fibre Channel devices include FGA0 and FGB0.
Fibre Channel path names are craeted by concatenating the SCSI pseudodevice name, a decimal point (.), and the WWID of the storage subsystem port that is being accessed: for example, PGB0.4000-1FE1-0000-0D04. Refer to Guidelines for OpenVMS Cluster Configurations, chapter 6, for more details on FC path names.
See also
- VSI Guidelines for OpenVMS Cluster Configurations on configuring FC as an OpenVMS Cluster storage interconnect and multipath configurations
- HP StorageWorks SAN Design Reference Guide on using Fibre Channel for SANs
- The official FC website] for the latest information on Fibre Channel and related technologies
