Abstract: A computer implemented method, apparatus, and computer usable program product for managing redundant array of independent drives. In response to a failure of a hard disk in a first RAID array, the process calculates an amount of free capacity available across a set of remaining hard disks in the first RAID array. The set of remaining hard disks comprises every hard disk associated with the first RAID array except the failed disk. In response to a determination that the amount of free capacity is sufficient to re-create the first RAID array at a same RAID level, the process reconstructs the first RAID array using an amount of space in the set of remaining drives utilized by the first RAID array and the free capacity to form a new RAID array without utilizing a spare hard disk.

Abstract: Data storage reliability is maintained in a write-back distributed data storage system including multiple nodes, each node comprising a processor and an array of failure independent data storage devices. Information is stored as a set of stripes, each stripe including a collection of multiple data strips and associated parity strips, the stripes distributed across multiple corresponding primary data nodes and multiple corresponding parity nodes. A primary data node maintains the data strip holding a first copy of data, and each parity node maintains a parity strip holding a parity for the multiple data strips. A read-modify-write parity update protocol is performed for maintaining parity coherency, the primary data node driving parity coherency with its corresponding parity nodes, independently of other data nodes, in order to keep its relevant parity strips coherent.

Abstract: Data storage reliability is maintained in a write-back distributed data storage system including multiple nodes. Information is stored as a stripe including a collection of a data strips and associated parity strips, the stripe distributed across data and parity nodes. Each data node maintains the data strip holding a first copy of data, and each parity node maintains a parity strip holding a parity for the collection of data strips. A driver node initiates a full-stripe-write parity update protocol for maintaining parity coherency in conjunction with other nodes, to keep the relevant parity strips coherent. Parity is determined directly by computing parity strips for all data strips of a stripe. Any node may function as a driver node.

Abstract: Data storage reliability is maintained in a write-back distributed data storage system including multiple nodes. Each node comprises a processor and an array of failure independent data storage devices. Information is stored as a set of stripes, each stripe including a collection of at least a data strip and associated parity strips, the stripes distributed across a primary data node and multiple corresponding parity nodes. A read-other parity update protocol maintains parity coherency. The primary data node for each data strip drives parity coherency with the corresponding parity nodes, independently of other data nodes, in keeping relevant parity strips for the primary data node coherent. A parity value is determined based on data other than a difference between new data and existing data. A new parity value is based on new data and dependent data, wherein with respect to one data value, dependent data comprises other data encoded in a corresponding parity value.

Abstract: Rebuilding lost data in a distributed redundancy data storage system including multiple nodes, is provided. User data is stored as a collection of stripes, each stripe comprising a collection of data strips and associated parity strips, the stripes distributed across multiple corresponding data owner nodes and multiple corresponding parity owner nodes. A data owner node maintains the associated data strip holding a first copy of data, and a parity owner node maintains a parity strip holding a parity for the collection of data strips. Upon detecting a failure condition, the owner node initiates a rebuilding protocol for recovery of lost data and/or parity it owns. The protocol includes reconstruction of lost data or parity by a computation involving data and/or parity from a recovery strip set in a stripe, wherein a recovery strip set contains at least one surviving data or parity strip. The recovery strip set for a lost data strip contains at least one surviving parity strip.

Abstract: Data validation systems and methods are provided. Data is recorded in N data chunks on one or more storage mediums. A first validation chunk independently associated with said N data chunks comprises first validation information for verifying accuracy of data recorded in said N data chunks. The first validation chunk is associated with a first validation appendix comprising second validation information, wherein the first validation appendix is stored on a first storage medium independent of said one or more storage mediums.

Abstract: A RAID system is provided for detecting and correcting dropped writes in a storage system. Data and a checksum are written to a storage device, such as a RAID array. The state of the data is classified as being in a “new data, unconfirmed” state. The state of written data is periodically checked, such as with a timer. If the data is in the “new data, unconfirmed” state, it is checked for a dropped write. If a dropped write has occurred, the state of the data is changed to a “single dropped write confirmed” state and the dropped write error is preferably corrected. If no dropped write is detected, the state is changed to a “confirmed good” state. If the data was updated through a read-modified-write prior to being checked for a dropped write event, its state is changed to an “unquantifiable” state.

Abstract: A RAID system is provided for detecting and correcting dropped writes in a storage system. Data and a checksum are written to a storage device, such as a RAID array. The state of the data is classified as being in a “new data, unconfirmed” state. The state of written data is periodically checked, such as with a timer. If the data is in the “new data, unconfirmed” state, it is checked for a dropped write. If a dropped write has occurred, the state of the data is changed to a “single dropped write confirmed” state and the dropped write error is preferably corrected. If no dropped write is detected, the state is changed to a “confirmed good” state. If the data was updated through a read-modified-write prior to being checked for a dropped write event, its state is changed to an “unquantifiable” state.

Abstract: Methods are provided for detecting and correcting dropped writes in a storage system. Data and a checksum are written to a storage device, such as a RAID array. The state of the data is classified as being in a “new data, unconfirmed” state. The state of written data is periodically checked, such as with a timer. If the data is in the “new data, unconfirmed” state, it is checked for a dropped write. If a dropped write has occurred, the state of the data is changed to a “single dropped write confirmed” state and the dropped write error is preferably corrected. If no dropped write is detected, the state is changed to a “confirmed good” state. If the data was updated through a read-modified-write prior to being checked for a dropped write event, its state is changed to an “unquantifiable” state.

Abstract: Method, system and computer program product are provided for detecting and correcting dropped writes in a storage system. Data and a checksum are written to a storage device, such as a RAID array. The state of the data is classified as being in a “new data, unconfirmed” state. The state of written data is periodically checked, such as with a timer. If the data is in the “new data, unconfirmed” state, it is checked for a dropped write. If a dropped write has occurred, the state of the data is changed to a “single dropped write confirmed” state and the dropped write error is preferably corrected. If no dropped write is detected, the state is changed to a “confirmed good” state. If the data was updated through a read-modified-write prior to being checked for a dropped write event, its state is changed to an “unquantifiable” state.

Abstract: Data validation systems and methods are provided. Data is recorded in N data chunks on one or more storage mediums. A first validation chunk independently associated with said N data chunks comprises first validation information for verifying accuracy of data recorded in said N data chunks. The first validation chunk is associated with a first validation appendix comprising second validation information, wherein the first validation appendix is stored on a first storage medium independent of said one or more storage mediums.

Abstract: Data validation systems and methods are provided. Data is recorded in N data chunks on one or more storage mediums. A first validation chunk independently associated with said N data chunks comprises first validation information for verifying accuracy of data recorded in said N data chunks. The first validation chunk is associated with a first validation appendix comprising second validation information, wherein the first validation appendix is stored on a first storage medium independent of said one or more storage mediums.

Abstract: A computer implemented method, apparatus, and computer usable program product for managing redundant array of independent drives. In response to a failure of a hard disk in a first RAID array, the process calculates an amount of free capacity available across a set of remaining hard disks in the first RAID array. The set of remaining hard disks comprises every hard disk associated with the first RAID array except the failed disk. In response to a determination that the amount of free capacity is sufficient to re-create the first RAID array at a same RAID level, the process reconstructs the first RAID array using an amount of space in the set of remaining drives utilized by the first RAID array and the free capacity to form a new RAID array without utilizing a spare hard disk.

Abstract: Methods are provided for detecting and correcting dropped writes in a storage system. Data and a checksum are written to a storage device, such as a RAID array. The state of the data is classified as being in a “new data, unconfirmed” state. The state of written data is periodically checked, such as with a timer. If the data is in the “new data, unconfirmed” state, it is checked for a dropped write. If a dropped write has occurred, the state of the data is changed to a “single dropped write confirmed” state and the dropped write error is preferably corrected. If no dropped write is detected, the state is, changed to a “confirmed good” state. If the data was updated through a read-modified-write prior to being checked for a dropped write event, its state is changed to an “unquantifiable” state.

Abstract: Method, system and computer program product are provided for detecting and correcting dropped writes in a storage system. Data and a checksum are written to a storage device, such as a RAID array. The state of the data is classified as being in a “new data, unconfirmed” state. The state of written data is periodically checked, such as with a timer. If the data is in the “new data, unconfirmed” state, it is checked for a dropped write. If a dropped write has occurred, the state of the data is changed to a “single dropped write confirmed” state and the dropped write error is preferably corrected. If no dropped write is detected, the state is changed to a “confirmed good” state. If the data was updated through a read-modified-write prior to being checked for a dropped write event, its state is changed to an “unquantifiable” state.

Abstract: Data validation systems and methods are provided. Data is recorded in N data chunks on one or more storage mediums. A first validation chunk independently associated with said N data chunks comprises first validation information for verifying accuracy of data recorded in said N data chunks. The first validation chunk is associated with a first validation appendix comprising second validation information, wherein the first validation appendix is stored on a first storage medium independent of said one or more storage mediums.

Abstract: A collective storage system and method for restoring data in the system after a failure in the system. The system includes multiple storage nodes that are interconnected by a network and store data as extents. There are also a set of Data Service (DS) agents for managing the extents, a set of Metadata Service (MDS) agents for managing metadata relating to the nodes and the extents, and a Cluster Manager (CM) agent in each node. After a node failure is detected by one of the CM agents, the agents responsible for coordinating the data restoring are notified of the failure. The agents generate a plan to restore the data extents affected by the failure, and then collectively restoring the affected extents based on the generated plan. The coordinating agents might be the MDS agents or DS agents. The failure might be a node failure or a disk failure.

Abstract: A collective storage system and method for restoring data in the system after a failure in the system. The system includes multiple storage nodes that are interconnected by a network and store data as extents. There are also a set of Data Service (DS) agents for managing the extents, a set of Metadata Service (MDS) agents for managing metadata relating to the nodes and the extents, and a Cluster Manager (CM) agent in each node. After a node failure is detected by one of the CM agents, the agents responsible for coordinating the data restoring are notified of the failure. The agents generate a plan to restore the data extents affected by the failure, and then collectively restoring the affected extents based on the generated plan. The coordinating agents might be the MDS agents or DS agents. The failure might be a node failure or a disk failure.

Abstract: A configuration management subsystem of a subsystem array system assigns heat producing devices to clusters such that the number of devices activated will not create overheating, regardless of which limited set of clusters is activated. The subsystem receives the dimensions of the disk array, the number of devices, the number of cluster groups and the maximum number of clusters that can be operated substantially simultaneously, and the dimensions of a critical box that defines an arrangement of the devices into cells such that, if a device is assigned to each cell of the critical box and all devices are operated simultaneously, then thermal operating restrictions of the devices will be exceeded. The system first executes simple numbering loop operations to determine, if they exist, dimensions of a building block subarray that meet certain requirements relative to the input parameters.

Abstract: A technique which efficiently approximates a continuous function employs volummetric linear interpolation and implements the interpolation process in an arithmetic apparatus which calculates a value v of the function according to: ##EQU1## where u.sub.i are scaling factors corresponding to specifically known points p.sub.i in a n-dimensional domain space of the function, v.sub.i are specifically known points in an m-dimensional range space of the function and k+1 is the number of specifically known points.