Abstract: A method for communication between an initiator system and a block storage cluster may include receiving a first input/output (I/O) request from the initiator system. The method may also include sending a referral response from a first storage system included in a plurality of storage systems of the block storage cluster to the initiator system when data associated with the first I/O request is stored in more than one storage system of the plurality of storage systems of the block storage cluster. Additionally, the method may include directing a referral I/O to the first storage system and the second storage system for transferring data to or transferring data from the first storage system and the second storage system, and transferring data associated with the referral I/O to or transferring data associated with the referral I/O from the first storage system and the second storage system.

Abstract: The present invention is a system utilizing multicast with distributed intelligence including an initiator device for transmitting a request, the request being addressed to a multicast group. The system also includes a switch for receiving the request from the initiator device. The switch is configured with multicast functionality for multicasting copies of the request to the multicast group. Additionally, the system includes a plurality of multicast group devices, each configured for receiving a copy of the request from the initiator device, via the switch. Each device of the plurality of multicast group devices is further configured with mapping functionality for allowing the storage device to determine a storage layout of the multicast group device. The initiator device, switch and each device of the plurality of multicast group devices are communicatively coupled via a network.

Abstract: The present invention is a method for providing multi-pathing via Small Computer System Interface Input/Output (SCSI I/O) referral between an initiator and a storage cluster which are communicatively coupled via a network, the storage cluster including at least a first target device and a second target device. The method includes receiving an input/output (I/O) at the first target device from the initiator via the network. The I/O includes a data request. The method further includes transmitting a SCSI I/O referral list to the initiator when data included in the data request is not stored on the first target device, but is stored on the second target device. The referral list includes first and second port identifiers for identifying first and second ports of the second target device respectively. The first and second ports of the target device are identified as access ports for accessing the data requested in the data request.

Abstract: A command is issued to a first data storage system for addressing a set of data and at least one of a first referral response including a referral to at least a second data storage system or at least a first subset of the set of data and the first referral response including the referral to the at least the second data storage system. The at least one of a first referral response including a referral to at least a second data storage system or at least a first subset of the set of data and the first referral response including the referral to the at least the second data storage system is accessed. A command is issued to the second data storage system for addressing the set of data and a second referral response including a referral to at least one of the first data storage system and a third data storage system, the second data storage system including at least a second subset of the set of data.

Abstract: The present invention is a method for providing multi-pathing via Small Computer System Interface Input/Output (SCSI I/O) referral between an initiator and a storage cluster which are communicatively coupled via a network, the storage cluster including at least a first target device and a second target device. The method includes receiving an input/output (I/O) at the first target device from the initiator via the network. The I/O includes a data request. The method further includes transmitting a SCSI I/O referral list to the initiator when data included in the data request is not stored on the first target device, but is stored on the second target device. The referral list includes first and second port identifiers for identifying first and second ports of the second target device respectively. The first and second port identifiers are SCSI relative port identifiers. The first and second ports of the target device are identified as access ports for accessing the data requested in the data request.

Abstract: The present invention is a method for communication between an initiator system and a block storage cluster. The method includes receiving a command at a first storage system of a block storage cluster. The command is transmitted by the initiator system to the first storage system via a network and includes a request for data. The method further includes transferring the stored data from the first storage system to the initiator system via the network when data requested in the data request is stored by the first storage system. The method further includes transmitting a referral response from the first storage system to the initiator system when a portion of the data requested in the data request is not stored by the first storage system, but is stored by a second storage system of the block storage cluster. The referral response indicates to the initiator system that: a) not all of the requested data was transferred; and b) that the second storage system stores the portion of the requested data.

Abstract: A method for recovering data from a redundant storage object comprises a command, executable upon a redundant storage object, which provides a mechanism for discovering the existence of copies of the data image and the number of copies of the data image available. The present invention further provides the capability of retrieving a copy of the data image(s) from underlying virtualization layers. By querying specific layers of the IO path to determine if a specific layer has copies of the data image, the number of copies may be determined and specified copies of the data image retrieved. This allows higher layers within a system to perform recovery if incorrect data is detected.

Abstract: A method for recovering data from a redundant storage object comprises a command, executable upon a redundant storage object, which provides a mechanism for discovering the existence of copies of the data image and the number of copies of the data image available. The present invention further provides the capability of retrieving a copy of the data image(s) from underlying virtualization layers. By querying specific layers of the IO path to determine if a specific layer has copies of the data image, the number of copies may be determined and specified copies of the data image retrieved. This allows higher layers within a system to perform recovery if incorrect data is detected.

Abstract: A portion of a storage controller's cache memory is used as a virtual solid state disk storage device to improve overall storage subsystem performance. In a first embodiment, the virtual solid state disk storage device is a single virtual disk drive for storing controller based information. In the first embodiment, the virtual solid state disk is reserved for use by the controller. In a second embodiment, a hybrid virtual LUN is configured as one or more virtual solid state disks in conjunction with one or more physical disks and managed using RAID levels 1-6. Since the hybrid virtual LUN is in the cache memory of the controller, data access times are reduced and throughput is increased by reduction of the RAID write penalty. The hybrid virtual LUN provides write performance that is typical of RAID 0. In a third embodiment, a high-speed virtual LUN is configured as a plurality of virtual solid state disks and managed as an entire virtual RAID LUN.

Abstract: A system for interconnecting a plurality of interdependent fiber channel loops or fabrics. The system preferably comprises a first server which includes a PCI bus and a fibre channel to PCI bus adapter for each one of the plurality of the independent fibre channels. Each fibre channel to PCI bus adapter is configured to connect one of the plurality fibre channels to the PCI bus at the first server. The plurality of independent fibre channels then communicate with each other across the PCI bus of the first server utilizing the intelligent I/O (I2O) routing of the fibre channel to PCI bus adapters. The plurality of fibre channels are configured to communicate with the other fibre channels, as well as the first server via the PCI bus. This system can be configured such that any one of the plurality of fibre channels can include one or more devices connected thereto in addition to the first server.

Abstract: Methods and associated apparatus for performing concurrent I/O operations on a common shared subset of disk drives (LUNs) by a plurality of RAID controllers. The methods of the present invention are operable in all of a plurality of RAID controllers to coordinate concurrent access to a shared set of disk drives. The plurality of RAID controllers operable enhance the performance of a RAID subsystem by better utilizing available processing power among the plurality of RAID controllers. Each of a plurality of RAID controllers may actively process different I/O requests on a common shared subset of disk drives. One of the plurality of controllers is designated as primary with respect to a particular shared subset of disk drives. The plurality of RAID controllers then exchange messages over a communication medium to coordinate concurrent access to the shared subset of disk drives through the primary controller.

Abstract: A system for globally prioritizing and scheduling I/O requests from a plurality of storage users or clients to one or more storage objects. The system comprises a storage controller configured to receive I/O requests from the client workstations and prioritize and schedule those I/O requests in accordance with a scheduling algorithm. Specifically, the storage controller receives I/O requests from the storage users and places the I/O requests in memory queues associated with the particular storage users. The storage controller then selects the I/O requests from the various memory queues based on the scheduling algorithm.

Abstract: Methods and associated apparatus for balancing the I/O request processing load within a plurality of controllers in a storage subsystem. The methods of the present invention are operable within interconnected controllers of a storage subsystem to shift the processing of received I/O requests to less loaded controllers and to do so in a manner transparent to legacy attached host systems. In a first embodiment of the present invention referred to as back-end load balancing, I/O requests are transferred from a first controller, to which the I/O request was directed by the attached host system, to a second controller for further processing. In this back-end load balancing embodiment, all write data associated with a write request as well as returned information including status or read data, is exchanged between the first and second controllers such that the first controller performs all communication with the attached host system.

Abstract: Methods and associated apparatus for performing concurrent I/O operations on a common shared subset of disk drives (LUNs) by a plurality of RAID controllers. The methods of the present invention are operable in all of a plurality of RAID controllers to coordinate concurrent access to a shared set of disk drives. In addition to providing redundancy features, the plurality of RAID controllers operable in accordance with the methods of the present invention enhance the performance of a RAID subsystem by better utilizing available processing power among the plurality of RAID controllers. Under the methods of the present invention, each of a plurality of RAID controllers may actively process different I/O requests on a common shared subset of disk drives. One of the plurality of controllers is designated as primary with respect to a particular shared subset of disk drives.

Abstract: In a redundant server network system, failover services for a failed server are provided by a survivor server belonging to a common failover group. At startup of a local server process running on the survivor server, a context is created for the local server and for each remote server belonging to the same failover group as the local server. At startup the context of the local server is also activated. The local server process is configured to operate on and make decisions based upon activated contexts. Each context includes server specific configuration and control information. When the survivor server must provide failover services for a failed server belonging to its same failover group, the context corresponding to the failed remote server is activated.

Abstract: Methods and associated apparatus within a RAID subsystem having redundant controllers define a private LUN as a data storage area known and accessible to all controllers in the system and used by them for diagnostic purposes. The methods involve sending a diagnostic write command to a first controller with instructions for it to write test data to the private LUN. This first controller writes this test data to the private LUN. A second controller, in response to another diagnostic command, then reads this test data from the private LUN and compares it to expected values provided in the diagnostic command. Using the results, it can then be determined which controller, if any, failed. If the first controller fails, then the second controller takes over ownership of portions of the data storage area assigned to the first controller. The private LUN is preferably striped across all channels used by the controllers to communicate to commonly attached disk drives.

Abstract: Methods and associated apparatus for coordinating file lock requests from a cluster of attached host computer systems within I/O controllers (e.g., intelligent I/O adapters) attached to a storage subsystem. The I/O controllers, operable in accordance with the methods of the present invention, includes semaphore tables used to provide temporary exclusive access to an identified portion of an identified file. The host systems request the temporary exclusive access of a file through the I/O controllers rather than over slower network communication media and protocols as is known in the art. The I/O controllers then manages a plurality of competing lock requests to provide mutual exclusivity of the file access. The file lock management is therefore managed over the higher bandwidth storage interface channels of the host systems and without the generalized network protocols burdening the lock management process and the host system CPUs.

Abstract: Methods and associated apparatus in a RAID storage subsystem to enhance the performance of write operations for sequences of large buffers generally non-aligned with stripe boundaries in the RAID storage subsystem. In particular, the methods identify a starting non-aligned portion of each large buffer to be written to the RAID storage subsystem, an ending non-aligned portion of each large buffer to be written to the RAID subsystem, and a larger middle portion of the large buffer to be written to the RAID subsystem which is aligned with stripe boundaries of the RAID storage subsystem. The stripe-aligned middle portion is written to the RAID storage devices in a cache write through mode using stripe write operations to maximize data throughput. The starting and ending portions identified by the methods of the present invention are written to the cache memory in a write back mode such that they will eventually be posted to the RAID storage devices in due course through normal RAID processing.

Abstract: A method for partitioning a disk array into logical storage units distinct from the physical storage units within the array. A set of individual drives within the array are partitioned into multiple partitions. Corresponding partitions from the individual drives are grouped together to form a logical unit which is addressed as, and functions as, an independent disk array. The partitions within the logical unit are addressed as, and function as, disk drives within the logical array. Thus, a single set of disk drives may be divided into two or more logical storage units, each functioning as an independent disk array, and each employing a different RAID level scheme for storing data. Alternatively, multiple sets of disk drives within the array can combined together into a logical storage unit which functions as a single set of drives. Corresponding drives from each set of drives are addressed as a single disk drive within the logical unit.