Abstract: Protection from uncorrectable media errors are provided for a RAID-configured storage system by a technique in which c redundancy information sectors are associated with n data information sectors. The n data sectors and c redundancy information sectors are then written as a single segment on a single storage unit. The RAID-configured storage system can be configured, for example, as a RAID 6 storage system, a RAID 5 storage system, a RAID 51 storage system, a RAID 3+3 storage system or a RAID N+3 storage system. The redundancy information can be based on a Reed-Solomon code, an XOR-based code, or one-dimensional parity.

Abstract: An intelligent router routes a user request to a storage server that is capable of handling that request natively, without emulation. The request is routed automatically, without any instruction or interaction on the part of the user. The intelligent router includes a storage tank-like computing environment and a set of intelligent routers. The set of intelligent routers appears as a single entity to users by presenting a single network IP address. When the intelligent router receives a request, it examines the protocol type and routes the request to one of the appropriate storage tank clients. The intelligent router does not change the contents of the request message, and thus the storage tank system do not become aware of the existence of the intelligent router. Consequently, any return messages do not need to go through the intelligent router, unless desired.

Abstract: Provided is a method for managing a network providing Input/Output (I/O) paths between a plurality of host systems and storage volumes in storage systems. An application service connection definition is provided for each connection from a host to a storage volume. At least one service level guarantee definition is provided indicating performance criteria to satisfy service requirements included in at least one service level agreement with at least one customer for network resources. Each service level guarantee definition is associated with at least one application service connection definition. Monitoring is performed as to whether Input/Output (I/O) requests transmitted through the multiple I/O paths satisfy performance criteria indicated in the service level guarantee definition associated with the I/O paths.

Abstract: Stored data can be recovered from a disk array having at least 2n+1 physical disks that are capable of storing n physical disks worth of data when any two disks fail, or when more than two dependent disks fail. Data is stored in data stripes that are divided into n substantially equal-sized strips and are distributed across the n disks. Each data stripe has a corresponding parity strip that is generated by including the data strips in the data stripe only once when the parity strip is generated. The data strips of each data stripe, the copy of each such data strip and the corresponding parity strip are distributed across the disks in such a manner that the data strips of each data stripe, the copy of each such data strip and the corresponding parity strip are each on a respectively different disk of the disk array.

Abstract: A data storage system and method for providing consistent data to multiple clients based on data modification information as existing data is updated and new data is written to the system. The information indicates the modification status of each data block and identifies which data blocks have been modified during a certain time interval. The clients may query and update the modification information by submitting requests through a request processor. The data modification information includes an Altered Block Map that indicates block modification status and a Toggle Block Map that identifies which blocks have been modified. The system further includes a Modification Counter a Pending Reset Counter for improved recognition and handling of the modified data.

Abstract: A distributed data storage system for sharing data among client computers running different types of operating systems by separating metadata from data. Data is stored in storage pools that are accessed by the client computers through a storage network. Metadata is stored in a metadata store and provided to the client computers by a cluster of metadata servers. The client computers communicate with the metadata servers using a Storage Tank protocol and over a control network. Each client computer runs an operating system-specific client program that provides the client side functions of the Storage Tank protocol. The client program preferably includes a file system interface for communicating with the file system in the storage system and user applications, a client state manager for providing data consistency, and a plurality of operating system services for communicating with the metadata servers.

Abstract: Systems and methods of increasing the performance of computer networks, especially networks connecting users to the Web, are provided. Performance is increased by reducing the latency the client experiences between sending a request to the server and receiving a response. A connection is obtained by a client device to the network target node addressed by a physical I/O address, to more quickly respond to requests for resource files on data storage devices. This enhancement may be implemented by connecting the controller of the data storage device directly to the network, to reduce the latency involved in mapping the logical I/O address into a physical I/O address. In that case the requested resource file is sent to the client directly by the data storage device controller, thus saving time otherwise spent in sending the request and data between computer network components.

Abstract: An intelligent router routes a user request to a storage server that is capable of handling that request natively, without emulation. The request is routed automatically, without any instruction or interaction on the part of the user. The intelligent router includes a storage tank-like computing environment and a set of intelligent routers. The set of intelligent routers appears as a single entity to users by presenting a single network IP address. When the intelligent router receives a request, it examines the protocol type and routes the request to one of the appropriate storage tank clients. The intelligent router does not change the contents of the request message, and thus the storage tank system do not become aware of the existence of the intelligent router. Consequently, any return messages do not need to go through the intelligent router, unless desired.

Abstract: A data storage system and method for providing consistent data to multiple clients based on data modification information as existing data is updated and new data is written to the system. The information indicates the modification status of each data block and identifies which data blocks have been modified during a certain time interval. The clients may query and update the modification information by submitting requests through a request processor. The data modification information includes an Altered Block Map that indicates block modification status and a Toggle Block Map that identifies which blocks have been modified. The system further includes a Modification Counter a Pending Reset Counter for improved recognition and handling of the modified data.

Abstract: A shared device environment having multiple nodes (4a-4c), each node containing a computer (6a-6c), an adaptor (8a-8c) and multiple storage devices (10a-10c). Adaptors (8a-8c) facilitate read access to storage devices (10a-10c) such that the data records accessed are the latest version data records. Adaptors (8a-8c) are operative to provide the latest version of data blocks requested by computers (6a-6c) by first searching the read cache of each adaptor for data blocks requested by computers (6a-6c). If the requested data blocks are not found in the read cache of any adaptors, then data structures (155, 156 and 158) within the adaptors are searched for any data blocks waiting to be added to the read cache of any adaptors. If no data blocks are found, then the read access is conducted directly from the storage device itself.

Abstract: Disclosed is a system for updating data at a data block. A first processing unit, such as an adaptor, receives update data. The data block to update is located in a first storage device, such as a hard disk drive, and a second storage device stores parity data for the data block. A parity group comprises a data block and corresponding parity data for the data block. The first processing unit obtains the data at the data block and calculates partial parity data from the data at the data block and the update data. The first processing unit stores the partial parity data in a storage area and writes the update data to the data block in the first storage device. The first processing unit further updates parity data for parity groups for which partial parity data is maintained by obtaining control of access to the parity group to update from a second processing unit, such as another adaptor, if the first processing unit does not control access to the parity group.

Abstract: Disclosed is a system for updating data. A first processing unit, such as an adaptor, receives a data update to a data block in a first storage device, such as a hard disk drive. Parity data for the data block is maintained in a second storage device. A parity group is comprised of the data block and the parity data. After determining that the first processing unit does not control access to the parity group including the data block to update, the first processing unit sends a message to a second processing unit, such as another adaptor, controlling access to the parity group requesting control of access to the parity group. The first processing unit determines new parity data from the data update, the data at the data block in the first storage device, and the parity data in the second storage device. The first processing unit then writes the data update to the data block in the first storage device and the new parity data to the second storage device.

Abstract: Multiple competing processors cooperatively manage access to a shared resource. Each processor separately stores a lock table, listing shared resource subparts, such as memory addresses of a data storage device, for example. The lock tables are stored in nonvolatile storage. In each lock table, each subpart is associated with a “state,” such as; LOCAL or REMOTE. In response to access requests from the hosts, the processors exchange various messages to cooperatively elect a single processor to have exclusive access to the subparts involved in the access requests. After one processor is elected, the lock-holding processor configures its lock table to show the identified subpart in the LOCAL state, and all non-lock-holding processors configure their lock tables to show the identified subpart in the REMOTE state. Thus, rather than replicating one lock table for all processors, the processors separately maintain lock tables that are coordinated with each other.

Abstract: A storage-controller-managed outboard incremental backup/restore of data. An indicator is assigned to an associated portion of data stored in a data storage device, wherein the indicator resides in a memory of a storage controller coupled to the data storage device. A value of the indicator residing within the memory of the storage controller is set when the associated portion of the data has changed. The associated portion of the data stored in the data storage device is backed using the storage controller when the value of the indicator residing within the memory of the storage controller is set. The value of the indicator residing within the memory of the storage controller is cleared when the associated portion of the data has been backed up.

Abstract: Multiple competing processors cooperatively manage access to a shared resource. Each processor separately stores a lock table, listing shared resource subparts, such as memory addresses of a data storage device, for example. The lock tables are stored in nonvolatile storage. In each lock table, each subpart is associated with a “state,” such as LOCAL or REMOTE. In response to access requests from the hosts, the processors exchange various messages to cooperatively elect a single processor to have exclusive access to the subparts involved in the access requests. After one processor is elected, the lock-holding processor configures its lock table to show the identified subpart in the LOCAL state, and all non-lock-holding processors configure their lock tables to show the identified subpart in the REMOTE state. Thus, rather than replicating one lock table for all processors, the processors separately maintain lock tables that are coordinated with each other.

Abstract: A method, apparatus, article of manufacture, and a memory structure for storing and retrieving data in physical sectors which are larger than the sector size presented to the user is disclosed. The method comprises the steps of receiving at least one user sector comprising write data, and writing the user sector to a portion of the physical sector of the storage device. In one embodiment, data is written to the data storage disk using existing data that was read from the storage disk for a RAID parity calculation.

Abstract: Disclosed is a system for updating and destaging data in a storage system. To overcome the limitations in the prior art described above, preferred embodiments of the present invention disclose a system for updating a data block in a storage device. A first processing unit receives an update to a data block in a storage device. The first processing unit sends a first message including the update and information indicating data blocks that were recently updated to a second processing unit. The second processing unit stores the update in a second storage area and sends a second message to the first processing unit after receiving the first message. The first processing unit stores the update in a first storage area and transfers the update from the first storage area to the data block in the storage device. The first processing unit transfers the update from the first storage area to the data block in the storage device.

Abstract: A data storage facility provides a remote copy operation that copies data write updates from a primary data store to a remote site by identifying which bytes in a block update have changed and sending only the changed bytes from the primary data store to the remote site. An exclusive-OR (XOR) logic operation is used to identify the changed bytes by XOR'ing the original data block with the changed block. Data compression can then be used on the XOR data block to delete the unchanged bytes, and when the compressed block is sent to the remote site, only the unchanged bytes will be sent, thereby reducing the bandwidth needed between the primary store and the remote site.

Abstract: Disclosed is a system for altering the structure of parity groups, e.g., altering the RAID level or number of storage devices included in the RAID array. A parity group consists of a set of data blocks and parity data for the data blocks. The data and parity data are stored in at least two storage devices. The first processing unit alters the parity structure of an Nth set of parity groups, wherein N is an integer value greater than or equal to zero. A set of parity groups includes at least one parity group. The second processing unit determines an Nth range of parity groups including the Nth set of parity groups. After detecting the failure of the first processing unit while altering the parity structure of the parity groups in the Nth set, the second processing unit processes the parity groups in the determined Nth range to determine a parity group whose parity structure was being altered when the first processing unit failed.

Abstract: Disclosed is a system for performing an operation, such as a read or write operation, on a data block in a shared disk system. A first adaptor receives a request to perform an operation on a data block maintained in a data storage location. The first adaptor then determines whether the first adaptor controls access to the data block. The first adaptor performs the requested operation on the data block after determining that the first adaptor controls access to the data block. If the first adaptor does not control access to the data block, then the first adaptor transmits a first message to a second adaptor that controls access to the data block and requests control of access to the data block. After receiving the first message, the second adaptor transfers control of access to the data block to the first adaptor. The second adaptor then transmits a second message to the first adaptor that the first adaptor controls access to the data block.