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 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: 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 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: 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, 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, 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 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 computer program product is disclosed for facilitating physical disk request scheduling. The apparatus is configured to queue disk requests onto a work queue; assign a priority identifier to each disk request in the work queue according to the relative importance of each disk request; determine a ranking index or I/O efficiency for each pending disk request based on the priority of each disk request, the elapsed time on the work queue for each disk request, and the access time calculated for each disk request. The invention has particular applicability to SCSI-3 environments.

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: The present invention relates to a method of providing an antihistaminic effect in a hepatically impaired patient in need thereof comprising administering to said patient an effective antihistaminic amount of a compound of the formula wherein R1 is hydrogen or hydroxy; R2 is hydrogen; or R1 and R2 taken together form a second bond between the carbon atoms bearing R1 and R2; n is an integer of from 1 to 5; R3 is —COOH or —COOalkyl wherein the alkyl moiety has from 1 to 6 carbon atoms and is straight or branched; each of A and B is hydrogen or hydroxy with the proviso that at least one of A or B is hydrogen; or a pharmaceutically acceptable salt and individual isomers thereof.

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: A method and apparatus for providing efficient management of LRU insertion points corresponding to defined times-in-cache is disclosed. Insertion points are implemented as “dummy entries” in the LRU list. As such, they undergo the standard process for aging out of cache, along with all other entries. A circular queue of insertion points is maintained. At regular intervals, a new insertion point is placed at the top of the LRU list, and at the tail of the queue. When an insertion point reaches the bottom of the LRU list (“ages out”), it is removed form the head of the queue. Since insertion points are added to the list at regular intervals, the remaining time for data at the corresponding LRU list positions to age out must increase in the same, regular steps, as we consider insertion points from the bottom to the top of the LRU list. Therefore, we can find an insertion point which exhibits any desired age-out time, by indexing into the circular queue.

Abstract: In a first form, a method for managing requests in a disk array having a number of disks includes associating priorities with respective requests. A new request is processed, which includes determining a maximum priority for at least certain ones of requests received and comparing the priority of the new request to the maximum priority. Responsive to the comparison, a selection is made between i) categorizing the new request as a foreground disk operation and ii) categorizing the new request as a background disk operation. A selection is also made between i) working the new request on at least one of the disks and ii) placing the new request in a queue.

Abstract: In a first form, a method for managing requests in a disk array having a number of disks includes associating priorities with respective requests. A new request is processed, which includes determining a maximum priority for at least certain ones of requests received and comparing the priority of the new request to the maximum priority. Responsive to the comparison, a selection is made between i) categorizing the new request as a foreground disk operation and ii) categorizing the new request as a background disk operation. A selection is also made between i) working the new request on at least one of the disks and ii) placing the new request in a queue.

Abstract: In a cache management system multiple cache lists are utilized, where each entry in a list names at least one corresponding data item in cache. A cache manager always demotes cache list entries from a “current removal list” (and demotes or destages the corresponding data items from cache) until that list is exhausted and another list rotates into the function of current removal list. A prescribed order is established for rotating the role of current removal list. In response to prescribed activities of data items in cache, new cache list entries are added nearer or farther from the current removal list according to the prescribed order and the data items' priorities.

Abstract: In a cache management system multiple cache lists are utilized, where each entry in a list names at least one corresponding data item in cache. A cache manager always demotes cache list entries from a “current removal list” (and demotes or destages the corresponding data items from cache) until that list is exhausted and another list rotates into the function of current removal list. A prescribed order is established for rotating the role of current removal list. In response to prescribed activities of data items in cache, new cache list entries are added nearer or farther from the current removal list according to the prescribed order and the data items' priorities.

Abstract: The present invention provides a method and system for reporting disk utilization in a computer system. The method includes collecting at least one parameter pertaining to a disk array in a disk subsystem by a processor in the disk subsystem; transferring the at least one parameter from the processor to an open system host; and calculating disk utilization based upon the at least one parameter. The method and system is able to provide disk utilization which is understandable to the open system host. In a preferred embodiment, the disk utilization is provided by collecting the relevant parameters from the microcode in the processor of the disk subsystem, and then calculating the average disk utilization per disk based upon the parameters. Thus, an open system host is able to obtain a useful characteristic for determining the performance of the disk subsystem.