Abstract: A mechanism is provided in a cache subsystem for cache prefetching based on non-sequential access. The mechanism determines frequently accessed non-sequential cache records in the cache subsystem. The mechanism collects trailing record statistics for the frequently accessed non-sequential cache records. The mechanism determines a caching strategy. The caching strategy comprises prefetching a set of trailing records responsive to a read of a given frequently accessed non-sequential cache record. The mechanism applies the caching strategy to the cache subsystem.

Abstract: A mechanism is provided in a cache subsystem for cache prefetching based on non-sequential access. The mechanism determines frequently accessed non-sequential cache records in the cache subsystem. The mechanism collects trailing record statistics for the frequently accessed non-sequential cache records. The mechanism determines a caching strategy. The caching strategy comprises prefetching a set of trailing records responsive to a read of a given frequently accessed non-sequential cache record. The mechanism applies the caching strategy to the cache subsystem.

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: A mechanism is provided for optimizing free space collection in a storage system having a plurality of segments. A collection score value is calculated for least one of the plurality of segments. The collection score value is calculated by determining a sum, across tracks in the segment, of the amount of time over a predetermined period of time during which the track has been invalid due to a more recent copy being written in a different segment. Segments are chosen for free space collection based on the determined collection score value.

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: Method, system, and computer program product embodiments for facilitating deduplication product testing in a computing environment are provided. In one such embodiment, data to be processed through the deduplication product testing is arranged into a single, continuous stream. At least one of a plurality of random modifications are applied to the arranged data in a self-similar pattern exhibiting scale invariance. A plurality of randomly sized subsets of the arranged data modified with the self-similar pattern is mapped into each of a plurality of randomly sized deduplication test files.

Abstract: Data to be processed through deduplication product testing is arranged into a single, continuous stream. At least one of a plurality of random modifications are applied to the arranged data in a self-similar pattern exhibiting scale invariance. A plurality of randomly sized subsets of the arranged data modified with the self-similar pattern is mapped into each of a plurality of randomly sized deduplication test files.

Abstract: Methods, controllers for data storage, data storage systems, and computer program products are directed to migrating data after the initial placement of the data in data storage entities having higher speed and in other data storage. Steps of a method to migrate data to the higher speed data storage are (1) identifying at least one group of data having had at least one I/O activity in each of a plurality of intervals of time, occurring over a string of multiple intervals of time, wherein the I/O activity is with respect to the other data storage from which data is to be migrated. The time for each of the multiple intervals is selected such that bursts of the I/O activity are likely to be contained in one interval. (2) The identified group of data is classified to the higher speed data storage and migrated.

Abstract: Data to be processed through deduplication product testing is arranged into a single, continuous stream. At least one of a plurality of random modifications are applied to the arranged data in a self-similar pattern exhibiting scale invariance. A plurality of randomly sized subsets of the arranged data modified with the self-similar pattern is mapped into each of a plurality of randomly sized deduplication test files.

Abstract: Methods, controllers for data storage, data storage systems, and computer program products are directed to migrating data after the initial placement of the data in data storage entities having higher speed and in other data storage. Steps of a method to migrate data to the higher speed data storage are (1) identifying at least one group of data having had at least one I/O activity in each of a plurality of intervals of time, occurring over a string of multiple intervals of time, wherein the I/O activity is with respect to the other data storage from which data is to be migrated. The time for each of the multiple intervals is selected such that bursts of the I/O activity are likely to be contained in one interval. (2) The identified group of data is classified to the higher speed data storage and migrated.

Abstract: Method, system, and computer program product embodiments for facilitating deduplication product testing in a computing environment are provided. In one such embodiment, data to be processed through the deduplication product testing is arranged into a single, continuous stream. At least one of a plurality of random modifications are applied to the arranged data in a self-similar pattern exhibiting scale invariance. A plurality of randomly sized subsets of the arranged data modified with the self-similar pattern is mapped into each of a plurality of randomly sized deduplication test files.

Abstract: Methods, controllers for data storage, data storage systems, and computer program products are directed to migrating data after the initial placement of the data in data storage entities having higher speed and in other data storage. Steps of a method to migrate data to the higher speed data storage are (1) identifying at least one group of data having had at least one I/O activity in each of a plurality of intervals of time, occurring over a string of multiple intervals of time, wherein the I/O activity is with respect to the other data storage from which data is to be migrated. The time for each of the multiple intervals is selected such that bursts of the I/O activity are likely to be contained in one interval. (2) The identified group of data is classified to the higher speed data storage and migrated.

Abstract: Provided are a method, system, and article of manufacture for using different algorithms to destage different types of data from cache. A first destaging algorithm is used to destage a first type of data to a storage for a first duration. A second destaging algorithm is used to destage a second type of data to the storage for a second duration.

Abstract: Provided are a method, system and article of manufacture for generating a value associated with one of a plurality of leaf nodes by implicitly randomly climbing an implicit tree having the leaf nodes. A determination is made of an ancestor node of a current node, wherein each ancestor node at a level of the ancestor node is associated with a different set of ordered leaf nodes, wherein there is a unique value associated with each leaf node. A determination is made of a first leaf node of the ordered leaf nodes associated with the determined ancestor node. A determination is made as to whether the determined ancestor node is a rightmost ancestor node at the level of the ancestor node. A first formula is used to determine a last leaf node of the ordered leaf nodes associated with the determined ancestor node in response to determining that the ancestor node is the rightmost ancestor node.

Abstract: Methods, controllers for data storage, data storage systems, and computer program products are directed to migrating data after the initial placement of the data in data storage entities having higher speed and in other data storage. Steps of a method to migrate data to the higher speed data storage are (1) identifying at least one group of data having had at least one I/O activity in each of a plurality of intervals of time, occurring over a string of multiple intervals of time, wherein the I/O activity is with respect to the other data storage from which data is to be migrated. The time for each of the multiple intervals is selected such that bursts of the I/O activity are likely to be contained in one interval. (2) The identified group of data is classified to the higher speed data storage and migrated.

Abstract: Method, system, and computer program product embodiments for facilitating deduplication product testing in a computing environment are provided. In one such embodiment, data to be processed through the deduplication product testing is arranged into a single, continuous stream. At least one of a plurality of random modifications are applied to the arranged data in a self-similar pattern exhibiting scale invariance. A plurality of randomly sized subsets of the arranged data modified with the self-similar pattern is mapped into each of a plurality of randomly sized deduplication test files.

Abstract: A method, system, computer program product, and computer program storage device for dynamically adjusting a maximum limit of concurrent service requests directed to a shared storage resource that can be issued by a plurality of host devices is disclosed. The method, system, computer program product, and computer program storage device operate based on a rotating turn, in which a host device has a chance to be able to increase its currently available maximum number of concurrent service requests.

Abstract: Provided are a method, system, and article of manufacture for using priority to determine whether to queue an Input/Output (I/O) request directed to storage. A maximum number of concurrent requests directed to a storage is measured. The measured maximum number of concurrent requests is used to determine a threshold for a specified priority. Subsequent requests of the specified priority directed to the storage are allowed to proceed in response to determining that a current number of concurrent requests for the specified priority does not exceed the determined threshold for the specified priority. Subsequent requests directed to the storage having a priority greater than the specified priority are allowed to proceed. Subsequent requests directed to the storage having the specified priority are queued in a queue in response to determining that the current number of concurrent requests for the specified priority exceeds the overall threshold.

Abstract: Provided are a method, system, and article of manufacture, where a plurality of extents are stored in a first set of storage units coupled to a controller. A determination is made that a second set of storage units has been coupled to the controller. The plurality of extents are distributed among all storage units included in the first set of storage units and the second set of storage units.

Abstract: Provided are a method, system, and article of manufacture for using different algorithms to destage different types of data from cache. A first destaging algorithm is used to destage a first type of data to a storage for a first duration. A second destaging algorithm is used to destage a second type of data to the storage for a second duration.