Abstract: Storage systems configured for improved N-way connectivity among all of a plurality of storage controllers and all of a plurality of storage devices in the system. All controllers of the storage system are coupled through a switched fabric communication medium to all of the storage devices of the storage system. Thus, the back-end interface of each storage controller of the storage system is used for all communications with any of the storage devices as well as for any communications among the controllers to coordinate the N-way distribution of stored data in a declustered RAID storage environment. This use of the back-end channel for all storage controller to storage device N-way connectivity as well as controller to controller N-way connectivity eliminates the need for a dedicated inter-controller interface for such N-way connectivity and eliminates the over-utilization of a front-end (e.g., network) communication path for providing N-way connectivity in the storage system.

Abstract: Storage systems configured for improved N-way connectivity among all of a plurality of storage controllers and all of a plurality of storage devices in the system. All controllers of the storage system are coupled through a switched fabric communication medium to all of the storage devices of the storage system. Thus, the back-end interface of each storage controller of the storage system is used for all communications with any of the storage devices as well as for any communications among the controllers to coordinate the N-way distribution of stored data in a declustered RAID storage environment. This use of the back-end channel for all storage controller to storage device N-way connectivity as well as controller to controller N-way connectivity eliminates the need for a dedicated inter-controller interface for such N-way connectivity and eliminates the over-utilization of a front-end (e.g., network) communication path for providing N-way connectivity in the storage system.

Abstract: Apparatus and methods for controllably spinning up disk drives in a storage system. A storage system includes a first portion of disk drives that support controllable sequencing of disk drive spin-up and a second portion that do not support controllable sequencing of spin-up. Disk drives in the first portion are configured to be powered on with the storage system and are controllably spun up by issuing appropriate commands to each disk drive. Disk drives in the second portion are configured initially powered off when the storage system is powered on and have power controllably applied thereto to cause spin-up of each disk drive. Disk drives in the first portion may include SAS disk drives and SATA disk drives that support staggered spin-up features. Disk drives in the second portion may include SATA disk drives that do not support staggered spin-up.

Abstract: A host interface dual active fibre channel adaptive hub includes two fibre channel arbitrated loops, a loop healing switch coupled to both loops, and four loop resiliency circuits. Each loop has a controller and a host server coupled to it through a respective loop resiliency circuit. The host servers issue I/O requests to the controllers through the dual fibre channel arbitrated loops. Therefore in normal operation, with both loops active and both controllers operational, the system provides twice the bandwidth of a conventional single loop fibre channel arbitrated loop system. The loop resiliency circuits detect failures in the controllers. If a loop resiliency circuit detects a failure in a controller, the loop resiliency circuit outputs a failure signal to the loop healing switch. A failed controller also notifies the loop healing switch that it has failed. The loop healing switch then switches to couple the two fibre channel arbitrated loops into a single loop.

Abstract: Adaptive write policy for handling host write commands to write-back system drives in a dual active controller environment. Method for adaptive write policy in data storage system, where data storage system includes host system connected to primary controller and alternate controller. Controllers are coupled to system drive that includes one or more disk storage devices. Primary is connected to first memory and alternate is connected to second memory. Primary and alternate manage data storage system in dual-active configuration. Primary controller receives host write command from host system and write data request includes host write data. When system drive is configured with write-back policy, primary determines whether host write command encompasses an entire RAID stripe, and if so, primary processes host write command in accordance with write-through policy. Otherwise, primary processes command in accordance with write-back policy.

Abstract: A method and apparatus for controlling a memory system 100 comprising a plurality of controllers 105 connected by a fibre channel arbitrated loop 145 to provide transparent failover and failback mechanisms for failed controllers. The controllers 105 are adapted to transfer data between a data storage system 120 and at least one host computer 110 in response to instructions therefrom. In the method, a unique identifier is provided to each controller 105. The operation of the controllers 105 is then monitored and, when a failed controller is detected, a failover procedure is performed on a surviving controller. The failover procedure includes disabling the failed controller and instructing the surviving controller to assume the identity of the failed controller. Thus, the surviving controller is capable of responding to instructions addressed to it and instructions addressed to the failed controller, and the failure of the failed controller is transparent to the host computer 110.

Abstract: Adaptive write policy for handling host write commands to write-back system drives in a dual active controller environment. Method for adaptive write policy in data storage system, where data storage system includes host system connected to primary controller and alternate controller. Controllers are coupled to system drive that includes one or more disk storage devices. Primary is connected to first memory and alternate is connected to second memory. Primary and alternate manage data storage system in dual-active configuration. Primary controller receives host write command from host system and write data request includes host write data. When system drive is configured with write-back policy, primary determines whether host write command encompasses an entire RAID stripe, and if so, primary processes host write command in accordance with write-through policy. Otherwise, primary processes command in accordance with write-back policy.

Abstract: The invention provides structure and method for controlling access to a shared storage device, such as a disk drive storage array, in computer systems and networks having a plurality of host computers. A method for controlling access to a hardware device in a computer system having a plurality of computers and at least one hardware device connected to the plurality of computers. The method includes the steps of associating a locally unique identifier with each the plurality of computers, defining a data structure in a memory identifying which particular ones of the computers based on the locally unique identifier may be granted access to the device; and querying the data structure to determine if a requesting one of the computers should be granted access to the hardware device.