Abstract: A mirrored data storage system utilizes a first host device and a local storage device for primary data storage and a second host device and a remote storage device for mirrored, fail-over storage on behalf of client devices. At periodic intervals (called checkpoints), the first host device initiates data synchronization between itself and the two storage devices and issues checkpoint information to ensure that each device maintains information for a common stable storage state. The local storage device synchronizes its stored data and forwards the checkpoint information to the remote storage device. The remote storage device maintains a copy (called a snapshot) of the data at the common stable storage state. Given the snapshot and the checkpoint information, the remote storage device can restore itself to the common stable storage state in the event of a failure of the first host device and/or the local storage device.

Abstract: In a storage environment or storage area network having multiple host devices and at least one storage array, the host devices access logical data volumes stored on the storage array through array controllers disposed in the storage array. Multiple host devices can request access to shared ones of the logical data volumes through multiple paths to multiple array controllers, but each logical data volume is controlled or owned by only one array controller at a time. Thus, ownership of shared logical data volumes is transferred between the array controllers as necessary on behalf of the requesting host devices. To prevent ownership transfers from occurring too often, however, ownership of the logical data volumes is made exclusive, or “sticky,” for a period of time after each transfer. During the exclusive ownership period of time, the ownership cannot be transferred.

Abstract: Methods and associated structure for updating and propagating firmware updates in a multiple redundant controller storage subsystem. The methods of the present invention assure that the storage subsystem remains operable processing host system I/O requests while the redundant controllers manage the firmware update process. At least one controller of a plurality of redundant controllers in the system remains available for processing of host I/O requests as the controllers manage the firmware update process. A management client process operable on an administrative system coupled to the first of the redundant storage controllers transfers a structured firmware file to the first redundant controller. The management client need perform no further management of the update process. Rather, the controller themselves manage the process in accordance with metadata stored within the firmware file along with the programmed instructions to be updated.

Abstract: A data structure contains sequence number metadata which identifies an input/output (I/O) operation such as a full stripe write on a redundant array of independent disks (RAID) mass storage system, and also contains revision number metadata which identifies a subsequent I/O operation such as a read modify write on only a fractional component of the entire user data. The sequence number and revision number metadata are used in an error detection and correction technique, along with parity metadata, to detect and correct silent errors arising from inadvertent data path and drive data corruption. An error to a portion of the stripe is detected by a difference in sequence numbers for all of the components of data. An error arising after an I/O operation is detected by a revision number which is different from the correct revision number.

Abstract: In a storage system, such as a storage area network, a snapshot volume or one or more checkpoint volumes are formed from the same base volume using a single repository containing multiple images of data stored in the base volume. The first image is started with the formation of the snapshot volume or the first checkpoint volume and is filled with blocks of data copied from the base volume, thereby increasing in size within the repository, until the first image is stopped and the next image is started. The next image is then filled with blocks of data copied from the base volume until stopped. Thus, the blocks of data are copied only into the most recently created image within the repository. With the creation of each checkpoint volume, a new image is concurrently started in the same repository. Each checkpoint volume is dependent on the image that was created concurrently plus any images created thereafter.

Abstract: A client machine (12) is connected to a network medium (20) for use in managing the operation of a plurality of subsystems (14-18) that are also coupled to the network medium (20). The client machine (12) includes a cache memory (26) for storing management-related objects that have been retrieved by the client machine (12) from the individual subsystems (14-18). When called upon to manage a particular subsystem, the client machine (12) first determines which management related objects will be required to manage the subsystem. The client machine (12) then checks the cache memory (26) to determine whether any of the required objects are located therein before requesting the objects from the associated subsystem. In this manner, only objects that are not available locally are requested from the subsystem, thereby reducing management-related information traffic in the network (10).

Abstract: A method of configuring a plurality of managed devices. The method preferably includes selecting a source managed device, obtaining a source configuration description from the source managed device, selecting one or more destination managed devices to be configured, issuing a configuration change command to each of the selected destination managed devices and applying the source configuration description selected from the source managed device to each of the selected destination managed devices. In addition, the method may further include the step of editing the source configuration description before issuing the configuration change commands to the one or more destination managed devices.

Abstract: This invention presents a method and system to emulate logging or journaling file systems by means of a snapshot mechanism. Use of the snapshot mechanism reduces the number of system bus calls during log or journal updates and recalls in case of file recovery. The snapshot mechanism is implemented in hardware to provide for speedy and reliable data transfers. Overall system performance thereby is improved with an average reduced number of calls to the system memory bus. The present invention offers a cost effective way of retrofitting existing file systems with a journaling or logging capability.

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: Sequence number metadata which identifies an input/output (I/O) operation, such as a full stripe write on a redundant array of independent disks (RAID) mass storage system, and revision number metadata which identifies an I/O operation such as a read modify write operation on user data recorded in components of the stripe, are used in an error detection and correction technique, along with parity metadata, to detect and correct silent errors arising from inadvertent data path and drive data corruption. An error arising after a full stripe write is detected by a difference in sequence numbers for all of the components of user data in the stripe. An error arising after a read modify write is detected by a revision number which occurred before the correct revision number.

Abstract: A system and method for monitoring and managing devices on a network. The system and method preferably comprises a proxy server connected to the network and a managed device connected to the proxy server. The system further comprises storage means for storing a device management application program associated with the managed device, and a management station in communication with the managed device via the proxy server and in communication with the storage means. The management station preferably is configured to retrieve the device management application program from the storage means and process the device management application program. As the management station processes the device management application program, the management station is able to monitor and manage the managed device.

Abstract: A system and method for monitoring and managing devices on a network. The system and method preferably comprises a proxy server connected to the network and a managed device connected to the proxy server. The system further comprises storage means for storing a device management application program associated with the managed device, and a management station in communication with the managed device via the proxy server and in communication with the storage means. The management station preferably is configured to retrieve the device management application program from the storage means and process the device management application program. As the management station processes the device management application program, the management station is able to monitor and manage the managed device.

Abstract: A system and method for managing device configuration changes. The system and method preferably comprises a management station which issues a configuration change request to a management device and waits for a reply from the managed device. The managed device receives the configuration change request from the management station and processes the change request until the configuration change request is durable on the managed device. The managed device then returns a status to the management station indicating that the configuration request is durable. The management station receives the status from the managed device and stops waiting for reply. In the meantime, the managed device continues processing the configuration change request.

Abstract: Data consistency is verified between geographically separated and connected active and mirroring data processing systems by creating metadata which describes user data, such as a cyclical redundancy code (CRC), and time stamp information which describes the time at which user data was first stored on the active system. The metadata and the time stamp information sent from the active system is compared at the mirroring system with the time stamp information and metadata read from the mirroring system. Upon detecting a discrepancy when comparing the metadata from the active and mirroring systems, the user data from the active or mirroring system which is less current temporally, as determined by the time stamp information, is replaced by the user data from the other one of the active or mirroring systems having the more current temporal time stamp information.

Abstract: Methods and associated structure for enabling immediate availability of a disk array storage device. In particular, the methods and associated structure of the present invention permit access to a logical unit of a storage system immediately following creation of the logical unit. Initialization of the logical unit to initialize redundancy information therein proceeds in parallel with host system access to the storage space of the logical unit. The initialization process maintains a boundary parameter value indicative of the progress of the initialization process. Storage space above the boundary has had its redundancy information initialized while storage space below the boundary has not. Where an I/O request is entirely above the boundary, it is processed normally in accordance with the management of the logical unit. Where part of an I/O request is below the boundary, it is processed in a special manner that assures integrity of the redundancy data.

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: An apparatus and method is disclosed which enables a host computer to adjust the caching strategy used for writing its write request data to storage media during execution of various software applications. The method includes the step of generating a caching-flushing parameter in the host computer. The cache flushing parameter is then transferred from the host computer to a controller which has a cache memory. Thereafter, a quantity of write request data is written from the cache memory to a storage medium in accordance with the cache-flushing parameter.

Abstract: An exemplary storage system for maintaining content (e.g. a Web site) for a shared network (e.g. the World Wide Web) includes content servers (e.g. Web servers) and storage devices connected together in a storage area network (SAN). A production server is used to develop new data to update the content of the Web site. The production server distributes the new data through the SAN to the storage devices, bypassing the Web servers. The Web servers are not involved in transferring the new data, so the Web servers preferably remain primarily dedicated to servicing Web page accesses from users across the Web.

Abstract: A graphical user interface is provided to represent relative and absolute physical locations of all RAID system components. Numerous graphical representations are defined. These graphical representations represent, in whole or in part, RAID system components such as disk drives, storage array controllers, controller and drive trays, power supplies, fans, software versions, hardware interfaces, connectors and/or cabling or wiring. The graphical representations are selected and arranged using a display screen. Their selection and arrangement are based on actual physical locations of their corresponding system components. The combined graphical representations can be used to check status of one or more system components, find and access the actual system components and/or update, either under user control or system control, the graphical representations to reflect any changes made to the corresponding actual RAID system components.

Abstract: The present invention provides storage system controllers and methods of controlling storage systems therewith. The controller (10) includes a main processor (12), a memory (14), a device interface (18) adapted to interface a peripheral component (28-32), such as a RAID storage device, with the storage system controller, and an operations sequencer (24). The main processor sequences a plurality of tasks to be executed to complete an operation. The operations sequencer coordinates an execution of the plurality of tasks. Methods of the invention include receiving a task status for each of the plurality of tasks that is executed, and issuing an interrupt to the main processor after all of the plurality of tasks of the operation are finished executing. In this manner, the operations sequencer offloads at least some of the main processor overhead to improve processor efficiency.