Arbitrated loop

Abstract: The Fibre Channel standard was created by the American National Standard for Information Systems (ANSI) X3T11 task group to define a serial I/O channel for interconnecting a number of heterogeneous peripheral devices to computer systems as well as interconnecting the computer systems themselves through optical fibre and copper media at gigabit speeds (i.e., one billion bits per second). Multiple protocols such as SCSI (Small Computer Serial Interface), IP (Internet Protocol), HIPPI, ATM (Asynchronous Transfer Mode) among others can concurrently utilize the same media when mapped over Fibre Channel. A Fibre Channel Fabric is an entity which transmits Fibre Channel frames between connected Node Ports. The Fibre Channel fabric routes the frames based on the destination address as well as other information embedded in the Fibre Channel frame header. Node Ports are attached to the Fibre Channel Fabric through links.

Abstract: Methods and apparatus for Fibre Channel interconnection is provided between a plurality of private loop devices through a Fibre Channel private loop device interconnect system. In the preferred embodiments, the Fibre Channel private loop device interconnect system is a fabric or an intelligent bridging hub. In one aspect of this invention, a Fibre Channel private loop device is connected to two or more Arbitrated Loops containing, or adapted to contain, one or more private loop devices. Preferably, the interconnect system includes a routing filter to filter incoming Arbitrated Loop physical addresses (ALPAs) to determine which Fibre Channel frames must attempt to be routed through the fabric. Numerous topologies of interconnect systems may be achieved. In another aspect of this invention, a method is provided for implementing a logical loop of private loop devices by segmenting the logical loop into a plurality of sets, assigning each set to a physical Arbitrated Loop and connecting the Arbitrated Loops to a Fibre Channel private loop device interconnect system. Additional methods are provided for restricting attached devices to Arbitrated Loop physical addresses within certain ranges. Additionally, methods are provided for resetting hosts, the method generally comprising the steps of detecting the addition of a storage device to a first Arbitrated Loop, and thereafter, resetting the Arbitrated Loop or loops on which a host or hosts reside on second Arbitrated Loop. Methods for operation with use of SCSI initiators generate a link service reject when no address match is found, or when an address match is found, but where no device with the destination ALPA exists on the Arbitrated Loop corresponding to the destination.

Abstract: A modular and highly available RAID system has a fiber channel arbitrated loop (FC-AL) interface coupled with a disk array Fault-tolerant operation is assured The system provides dual and isolated arbitrated host and storage device loop circuits for redundant, independent input/output (I/O) paths to local and/or remote host computers Each loop includes bypass circuits which prevent the failure of any device (host computer or storage device) from affecting the operation of loop Orthogonal data striping may be used to further assure data integrity

Abstract: A system for hierarchical data storage management and transparent data backup in a high speed, high volume Fibre Channel Arbitrated Loop environment comprising first and second Fibre Channel Arbitrated Loops, each coupling a Transaction Server and backup HSM server to high speed disk drives and mirrored high speed disk drives respectively. The two loops are coupled by a Bridge compatible with the Fibre Channel Arbitrated Loop protocol which forwards write transactions directed to the mirrored disk drives from the first loop the second but keeps read transaction from the Transaction Server to the high speed disk drives on the first loop isolated from backup and HSM transactions occurring on the second loop between the backup HSM server, the mirrored disk drives and backup storage devices coupled to the backup HSM server.