Abstract: Migrating a sub-volume in data storage with at least two de-duplication domains, each of the domains having at least one sub-volume. A first sub-volume is assigned to a de-duplication domain and a first content summary is computed for the first sub-volume. Similarly, a second sub-volume is assigned to a second de-duplication domains and a second content summary is computed for the second sub-volume. A first content affinity is calculated between the first sub-volume and a third sub-volume, and a second content affinity is calculated between the second sub-volume and the third sub-volume. A domain placement is selected for the third sub-volume based on comparison of the first content affinity and the second content affinity.

Abstract: Assignment of files to a de-duplication domain. Address space of data files is divided into multiple containers. For each of the containers, a file metadata scan is performed to obtain file system metadata, which is aggregated and summarized in a content feature summary. A content feature summary prediction measurement is measured between containers from the generated content feature summary, and files from each container are assigned to a de-duplication domain based upon the content similarity predication measurement.

Abstract: Aspects of the invention are provided for decoding a selected span of data within a compressed code stream. A selection of data within the compressed code stream from an arbitrary position is presented for decompression. The arbitrary position is the starting point in the compressed code stream for decompression, and a phrase within the compressed code stream containing the starting point is identified. From the arbitrary starting point, a back pointer may provide direction to the literal. The literal is extracted as a decoding of the compressed data associated with the starting point.

Abstract: For managing a storage server having improving overall system performance, a first input/output (I/O) request is received. A first priority level is dynamically assigned to the first I/O request, the first I/O request associated with a performance level for an application residing on a host in communication with the storage server. A second I/O request of a second priority level is throttled to allow at least a portion of a predetermined amount of resources previously designated for performing the second I/O request to be re-allocated to performing the first I/O request. The second priority level is different than the first priority level.

Abstract: Methods, apparatus and computer program products implement embodiments of the present invention that include identifying non-destaged first data in a write cache. Upon detecting second data in a master read cache, the second data is copied the second data to one or more backup read caches, and the second data is pinned to the master and the backup read caches. Using the first data stored in the write cache and the second data stored in the master read cache, one or more parity values are calculated, and the first data and the one or more parity values are destaged.

Abstract: Methods, apparatus and computer program products implement embodiments of the present invention that include defining, in a storage system including receiving, by a processor, metadata describing a first cache configured as a master cache having non-destaged data, and defining, using the received metadata, a second cache configured as a backup cache for the master cache. Subsequent to defining the second cache, the non-destaged data is retrieved from the first cache, and the non-destaged data is stored to the second cache.

Abstract: Methods, apparatus and computer program products implement embodiments of the present invention that include defining, in a storage system including receiving, by a storage system, a storage request, and identifying, based on the storage request, one or more storage management units. For each of the storage management units, a master partition table having multiple master entries and one or more backup partition tables is identified, each of the backup partition tables having backup entries in a one-to-one-correspondence with the master entries. The storage request is performed, and upon the storage request being performed, any changes to essential metadata in the one or more master partition tables are identified, and the identified changes are stored to the essential metadata in the one or more backup partition tables.

Abstract: Methods, apparatus and computer program products implement embodiments of the present invention that enable digital information devices having respective storage devices and memories to distributedly store, for a logical volume, data and first and second parity values across corresponding regions of the storage devices. Freezers having a one-to-one correspondence with the storage devices are distributedly stored in the memories. Upon detecting, in a cache, updated data for one or more first regions on the storage devices, existing data from the one or more first regions, and additional data for parity calculations are retrieved from one or more corresponding second regions on the storage devices, and first and the second parity values are calculated using the updated data, the existing data and the additional data. The updated data and the calculated first and second parity values are stored to the freezers, and then destaged from the freezers to the storage devices.

Abstract: Aspects of the invention are provided for decoding a selected span of data within a compressed code stream. A selection of data within the compressed code stream from an arbitrary position is presented for decompression. The arbitrary position is the starting point in the compressed code stream for decompression, and a phrase within the compressed code stream containing the starting point is identified. From the arbitrary starting point, a back pointer may provide direction to the literal. The literal is extracted as a decoding of the compressed data associated with the starting point.

Abstract: Embodiments of the invention relate to data placement for loss protection in a storage system. One embodiment includes constructing multiple logical compartments. Each logical compartment includes a placement policy including a set of storage placement rules for placement of storage symbols into a set of physical storage containers. A first logical compartment of said plurality of logical compartments is container-overlapped with respect to a second logical compartment of said plurality of logical compartments. The first logical compartment is data loss independent with respect to the second logical compartment. Each of multiple storage volumes is associated with a logical compartment. The storage symbols that represent a data stripe are placed onto physical storage containers in conformity with the placement policy associated with the logical compartment containing the data stripe.

Abstract: A data storage system comprising a Quality of Service server to optimize revenue realized under multiple service level agreements with a data storage client.

Abstract: Methods, systems, and physical computer-readable storage medium for processing a plurality of IO request jobs are provided. The method includes determining whether one or more request jobs are not meeting a QoS target, each job of the one or more request jobs having a corresponding priority, selecting a highest priority job from the one or more request jobs, if one or more request jobs are not meeting the QoS target, determining whether the highest priority job has a corresponding effective rate limit imposed thereon, if so, relaxing the corresponding effective rate limit, and if not, selecting one or more lower priority jobs from the one or more request jobs and tightening a corresponding effective limit on the one or more lower priority jobs from the one or more request jobs in accordance with a delay factor limit.

Abstract: Embodiments of the invention relate to dynamic power management of storage volumes and disk arrays in a storage subsystem to mitigate loss of performance resulting from the power management. The volumes and arrays are prioritized, and in real-time power is selectively reduced in response to both the prioritization and an energy savings goal. A feedback loop is provided to dynamically measure associated power gain based upon a lowering of power consumption, and device selection may be adjusted based upon received feedback.

Abstract: Provided are a method, system, and article of manufacture for authenticating a processing system accessing a resource. An association of processing system identifiers with resources, including a first and second resources, is maintained. A request from a requesting processing system in a host is received for use of a first resource that provides access to a second resource, wherein the request is generated by processing system software and wherein the request further includes a submitted processing system identifier included in the request by host hardware in the host. A determination is made as to whether the submitted processing system identifier is one of the processing system identifiers associated with the first and second resources. The requesting processing system is provided access to the first resource that the processing system uses to access the second resource.

Abstract: Embodiments relate to a method for data management. An aspect includes a method for assigning storage types to data based on access frequency. Past or historical data associated with current data usage is also considered prior to assignment. Once data frequency access is determined, the current data is assigned to a first tier of a plurality of hierarchical ordered tiers, each tier corresponding to at least one class of storage. In one embodiment, there may be a condition that overrides the assignment with option to override it. The tier assignment may also be preserved the tier so that the current data can be appropriately assigned in the future.

Abstract: Embodiments of the invention relate to dynamic power management of storage volumes and disk arrays in a storage subsystem to mitigate loss of performance resulting from the power management. The volumes and arrays are prioritized, and in real-time power is selectively reduced in response to both the prioritization and an energy savings goal. A feedback loop is provided to dynamically measure associated power gain based upon a lowering of power consumption, and device selection may be adjusted based upon received feedback.

Abstract: A method to optimize revenue realized under multiple service level agreements with multiple data storage clients is disclosed. The method provides an information storage and retrieval system. The method includes entering into (N) service level agreements to provide data storage services for (N) applications using the information storage and retrieval system, where each of the (N) service level agreements specifies an average maximum response time RTSLA. The method calculates for each value of (j), the value per unit throughput ?j for the (j)th application, and then determines for each value of (j) the optimum data flow rate x(j)OPT. The method estimates, for each value of (j), a maximum data flow rate X(j)MAX that the (j)th application can utilize, and determines, for each value of (j), if x(j)OPT equals X(j)MAX.

Abstract: Embodiments of the present invention provide a system, method and computer program products for estimating data reduction in a file system. A method includes selecting a sample of all data from data files in the file system, wherein said sample represent a subset of all the data in the file system. The method further includes estimating a data reduction ratio by data deduplication for the file system based on said sample. The method further includes estimating a data reduction ratio by data compression for the file system based said sample. The method further includes generating a combined data reduction estimate for the file system based on said data compression estimate and said data deduplication estimate.

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. 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.