Abstract: A storage system has a storage controller for an array of storage disks, the array being ordered in an sequence of write groups. A write cache is shared by the disks. The storage controller temporarily stores write groups in the write cache responsive to write groups being written to their respective arrays. The write groups are assigned to a global queue ordered by ages. The controller selects a quantity of write groups for attempted destaging to the arrays responsive to a predetermined high threshold for the global queue and to sizes and the ages of the write groups in the global queue, and allocates the selected quantity among the arrays responsive to quantities of certain ones of the write groups in the global queue. Write groups are destaged to respective arrays responsive to the selected allocation quantity for the array and the sequences of the write groups in the arrays.

Abstract: A method is disclosed for dynamically allocating main memory among applications. The method includes maintaining a first list and a second list, each list having a plurality of pages, maintaining a cache memory module having a selected size, and resizing the selected size by adaptively selecting the first or second list and adding pages to the selected list to increase the selected size and subtracting pages from the selected list to decrease the selected size.

Abstract: An apparatus and system are disclosed for dynamically allocating main memory among applications. The apparatus includes a cache memory module configured to maintain a first list and a second list, each list having a plurality of pages, and a resize module configured to resize the cache by adaptively selecting the first or second list and subtracting pages from or adding pages to the selected list. The system includes the apparatus and a cache replacement module configured to adaptively distribute a workload between the first list and the second list.

Abstract: A self-tuning, low overhead, simple to implement, locally adaptive, novel cache management policy that dynamically and adaptively partitions the cache space amongst sequential and random streams so as to reduce read misses.

Abstract: A self-tuning, low overhead, simple to implement, locally adaptive, novel cache management policy that dynamically and adaptively partitions the cache space amongst sequential and random streams so as to reduce read misses.

Abstract: A self-tuning, low overhead, simple to implements locally adaptive, novel cache management policy that dynamically and adaptively partitions the cache space amongst sequential and random streams so as to reduce read misses.

Abstract: Provided are a method, system, and article of manufacture for managing write requests in cache directed to different storage groups. A determination is made of a high and low thresholds for a plurality of storage groups configured in a storage, wherein the high and low thresholds for one storage group indicate a high and low percentage of a cache that may be used to store write requests to the storage group. A determination is made of a number of tasks to assign to the storage groups based on the determined high and low thresholds for the storage groups, wherein each task assigned to one storage group destages write requests from the cache to the storage group.

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: A self-tuning, low overhead, simple to implement, locally adaptive, novel cache management policy that dynamically and adaptively partitions the cache space amongst sequential and random streams so as to reduce read misses.

Abstract: A self-tuning, low overhead, simple to implement, locally adaptive, novel cache management policy that dynamically and adaptively partitions the cache space amongst sequential and random streams so as to reduce read misses.

Abstract: Provided are a method, system and program for using multiple data structures to manage data in cache. A plurality of data structures each have entries identifying data from a first computer readable medium added to a second computer readable medium. A request is received for data in the first computer readable medium. A determination is made as to whether there is an entry for the requested data in one of the data structures. The requested data is retrieved from the first computer readable medium to store in the second computer readable medium in response to determining that there is no entry for the requested data in one of the data structures. One of the data structures is selected in response to determining that there is no entry for the requested data in one of the data structures and an entry for the retrieved data is added to the selected data structure.

Abstract: A method of searching a database of documents, wherein the method includes performing a search of the database using a query to produce query result documents; constructing a word dictionary of words within the query result documents; constructing an out-link dictionary of documents within the database that are pointed to by the query result documents; adding the query result documents to the out-link dictionary; constructing an in-link dictionary of documents within the database that point to the query result documents; and adding the query result documents to the in-link dictionary.

Abstract: An adaptive replacement cache policy dynamically maintains two lists of pages, a recency list and a frequency list, in addition to a cache directory. The policy keeps these two lists to roughly the same size, the cache size c. Together, the two lists remember twice the number of pages that would fit in the cache. At any time, the policy selects a variable number of the most recent pages to exclude from the two lists. The policy adaptively decides in response to an evolving workload how many top pages from each list to maintain in the cache at any given time. It achieves such online, on-the-fly adaptation by using a learning rule that allows the policy to track a workload quickly and effectively.

Abstract: A method and system for dynamically allocating cache space in a storage system among multiple workload classes each having a unique set of quality-of-service (QoS) requirements. The invention dynamically adapts the space allocated to each class depending upon the observed response time for each class and the observed temporal locality in each class. The dynamic allocation is achieved by maintaining a history of recently evicted pages for each class, determining a future cache size for the class based on the history and the QoS requirements where the future cache size might be different than a current cache size for the class, determining whether the QoS requirements for the class are being met, and adjusting the future cache size to maximize the number of classes in which the QoS requirements are met. The future cache sizes are increased for the classes whose QoS requirements are not met while they are decreased for those whose QoS requirements are met.

Abstract: An adaptive replacement cache policy dynamically maintains two lists of pages, a recency list and a frequency list, in addition to a cache directory. The policy keeps these two lists to roughly the same size, the cache size c. Together, the two lists remember twice the number of pages that would fit in the cache. At any time, the policy selects a variable number of the most recent pages to exclude from the two lists. The policy adaptively decides in response to an evolving workload how many top pages from each list to maintain in the cache at any given time. It achieves such online, on-the-fly adaptation by using a learning rule that allows the policy to track a workload quickly and effectively. This allows the policy to balance between recency and frequency in an online and self-tuning fashion, in response to evolving and possibly changing access patterns. The policy is also scan-resistant.

Abstract: A method and system is provided for integrating multiple feature spaces in a k-means clustering algorithm when analyzing data records having multiple, heterogeneous feature spaces. The method assigns different relative weights to these various features spaces. Optimal feature weights are also determined that lead to a clustering that simultaneously minimizes the average intra-cluster dispersion and maximizes the average inter-cluster dispersion along all the feature spaces. Examples are provided that empirically demonstrate the effectiveness of feature weighting in clustering using two different feature domains.

Abstract: A method and computer program product for selectively making information available to groups of parties amongst a plurality of parties. Public keys that may be descriptive, such as a simple name or part of a name, are generated and published. Random suffixes or keys, which are random both in nature and in appearance, are generated, combined with public keys and distributed to members of groups selected to have access to secure data identified by a particular secure key. The random suffixes may be combined with the public keys to form a URL that appears to be simultaneously random and descriptive. Secure keys may be changed periodically, replacing the random suffix portion with a newly generated random suffix. Secure keys may be encryption keys derived from randomly generated decryption keys.

Abstract: A method and structure for performing a database search includes searching a database using a query (searching producing result items), and ranking the result items based on one or more of a frequency of an occurrence of in-links and out-links in each of the result items.

Abstract: A system and method are provided for lossy compression of finite alphabet source sequences subject to an average-per-letter distortion constraint. The source sequence is sequentially parsed into phrases and each source phrase is mapped to a distorted phrase such that average per-letter distortion between the two phrases does not exceed the desired distortion. The present system adaptively maintains a codebook as the collection of all one-letter extensions of previously emitted distorted phrases. The present system uses approximate string matching and carries out a sequential procedure by iterating the following steps: (i) given the current codebook find the longest source phrase that can be transmitted at a given distortion, (ii) from all codewords that match the source phrase carefully choose that which is most likely to be useful in the future.

Abstract: A computer-implemented system and method is for generating low-density parity check (LDPC) codes. One aspect of the invention includes a method for generating high rate LDPC codes that first constructs a matrix (H) of size m×n having m rows of check nodes and n columns of bit nodes. The matrix meets the following requirements: the weight of the j−th column equals aj; each row, r, has weight at most br; and the matrix H can be represented by a Tanner graph that has a girth of at least g≧g. The method then iteratively adds an (n+1)th column (U1) to matrix H, wherein the size of U1, is initially empty and is at most an+1, and wherein U1, comprises a set of i check nodes such that i is greater than or equal to 0 and i is less than an+1. The method then iteratively adds check nodes to U1. such that each check node does not violate predetermined girth and check-degree constraints. The matrix H is updated when a new column is added.