Raid system with fibre channel arbitrated loop

Claim 2

A controller for controlling communications between a plurality of host computer systems and a data storage subsystem, comprising: a first host loop; and a first plurality of port bypass circuits, each port bypass circuit connecting one of said plurality of host computer systems to said host loop, each port bypass circuit bypassing its associated host computer system if said associated host computer system becomes unavailable, wherein communication with remaining host computer systems is uninterrupted by said unavailable host computer system.

Claim 3

The controller of claim 1, further comprising: a second host loop operatively isolated from said first host loop; and a second plurality of port bypass circuits, each port bypass circuit connecting one of said plurality of host computer systems to said second host loop, each port bypass circuit bypassing its associated host computer system if said associated host computer system becomes unavailable, wherein communication with remaining host computer systems is uninterrupted by said unavailable host computer system, wherein said second host loop provides a redundant communication path to said host computer systems.

Claim 4

The controller of claim 2, where each of said first and second host loops comprises: a fiber channel arbitrated host loop.

Claim 5

A controller for controlling communications between a plurality of host computer systems and a plurality of storage devices, comprising: a first drive loop; and a first plurality of port bypass circuits, each port bypass circuit connecting one of said plurality of storage devices to said drive loop, each port bypass circuit bypassing its associated storage device if said associated storage device becomes unavailable, wherein communication with remaining storage devices is uninterrupted by said unavailable storage device.

Claim 6

A controller for controlling communications between a plurality of host computer systems and a plurality of storage devices, comprising: a first drive loop; and a first plurality of port bypass circuits, each port bypass circuit connecting one of said plurality of storage devices to said drive loop, each port bypass circuit bypassing its associated storage device if said associated storage device becomes unavailable, wherein communication with remaining storage devices is uninterrupted by said unavailable storage device.

Claim 7

The controller of claim 4, further comprising: a second drive loop operatively isolated from said first drive loop; and a second plurality of port bypass circuits, each port bypass circuit connecting one of said plurality of storage devices to said second drive loop, each port bypass circuit bypassing its associated storage device if said associated storage device becomes unavailable, wherein communication with remaining storage devices is uninterrupted by said unavailable storage device, wherein said second drive loop provides a redundant communication path to said plurality of storage devices.

Claim 8

The controller of claim 5, where each of said first and second drive loops comprises: a fiber channel arbitrated drive loop.

Claim 9

The controller of claim 6, further comprising: a first environmental control bus for monitoring the status of said plurality of storage devices; a first environmental bus control circuit for controlling said first plurality of port bypass circuits in response to input from said first environmental control bus.

Claim 10

The controller of claim 7, further comprising: a second environmental control bus for monitoring the status of said plurality of storage devices, said second environment control bus being operably isolated from said first environmental control bus to provide redundancy; a second environmental bus control circuit for controlling said second plurality of port bypass circuits in response to input from said second environmental control bus.

Claim 11

A modular and highly available fibre channel arbitrated loop system for ensuring fault-tolerant operation between a plurality of host computer systems and a data storage array having a plurality of storage devices, the system comprising: a first controller having a first arbitrated host loop coupling said first controller to a first host computer system; a first arbitrated drive loop coupling said first controller to the plurality of storage devices; a second controller having a second arbitrated host loop coupling said second controller to a second host computer system; a second arbitrated drive loop coupling said second controller to the plurality of storage devices, said second arbitrated host and second arbitrated drive loops being operatively isolated from said first arbitrated host and first arbitrated drive loops; host bypass means, operably connected between each of said arbitrated host loops and each host computer system, for bypassing an associated host computer system upon failure of said associated computer system, thereby ensuring continued operation of each of said arbitrated host loops; and drive bypass means, operably connected between each of said arbitrated drive loops and each of said storage devices, for bypassing an associated storage device upon failure of said associated device, thereby ensuring continued operation of each of said arbitrated drive loops.

Claim 12

A modular and highly available fibre channel arbitrated loop system for ensuring fault-tolerant operation between a plurality of host computer systems and a data storage array having a plurality of storage devices, the system comprising: a first controller having a first arbitrated host loop coupling said first controller to a first host computer system; a first arbitrated drive loop coupling said first controller to the plurality of storage devices; a second controller having a second arbitrated host loop coupling said second controller to a second host computer system; a second arbitrated drive loop coupling said second controller to the plurality of storage devices, said second arbitrated host and second arbitrated drive loops being operatively isolated from said first arbitrated host and first arbitrated drive loops; host bypass means, operably connected between each of said arbitrated host loops and each host computer system, for bypassing an associated host computer system upon failure of said associated computer system, thereby ensuring continued operation of each of said arbitrated host loops; and drive bypass means, operably connected between each of said arbitrated drive loops and each of said storage devices, for bypassing an associated storage device upon failure of said associated device, thereby ensuring continued operation of each of said arbitrated drive loops.

Claim 13

A RAID subsystem comprising: a plurality of disk modules, each disk module having a plurality of disk assemblies; a first controller having a first drive loop for communicating with said plurality of disk modules; a second controller having a second drive loop for communicating with said plurality of disk modules, wherein said second drive loop is operably isolated from said first drive loop; a plurality of first bypass circuits, each first bypass circuit connecting said first drive loop to one of said disk assemblies; and a plurality of second bypass circuits, each second bypass circuit connecting said second drive loop to one of said disk assemblies.

Claim 14

A RAID subsystem comprising: a plurality of disk modules, each disk module having a plurality of disk assemblies; a first controller having a first drive loop for communicating with said plurality of disk modules; a second controller having a second drive loop for communicating with said plurality of disk modules, wherein said second drive loop is operably isolated from said first drive loop; a plurality of first bypass circuits, each first bypass circuit connecting said first drive loop to one of said disk assemblies; and a plurality of second bypass circuits, each second bypass circuit connecting said second drive loop to one of said disk assemblies.

Claim 15

The RAID subsystem of claim 10, wherein each controller further comprises: a plurality of third bypass circuits interposed in said first and second drive loops for bypassing a failed disk module.

Claim 16

The RAID subsystem of claim 11, further comprising: a plurality of orthogonal logical units for storing data, each logical unit being formed from not more than one disk assembly of each disk module, wherein each of said orthogonal logical units can assure data integrity despite a failure of one of said disk modules.