Abstract: A method, system, and computer program product for preserving data in a storage subsystem having dual cache and dual nonvolatile storage (NVS) through a failover from a failed cluster to a surviving cluster is provided. A memory preserved indicator is initiated to mark tracks on a cache of the surviving cluster to be preserved, the tracks having an image in an NVS of the failed cluster. A destage operation is performed to destage the marked tracks. Subsequent to a determination that each of the marked tracks have been destaged, the memory preserved indicator is disabled to remove the mark from the tracks. If the surviving cluster reboots previous to each of the marked tracks having been destaged, the cache is verified as a memory preserved cache, the marked tracks are retained for processing while all unmarked tracks are removed, and the marked tracks are processed.

Abstract: An apparatus, system, and method are disclosed for selecting a space efficient repository. A cache receives write data. A destage module destages the data sequentially to a coarse grained repository such as a stride level repository and destages a directory entry for the data to a coarse grained directory such as a stride level directory if the data satisfies a repository policy. In addition, the destage module destages the data to a fine grained repository such as a track level repository overwriting an existing data instance and destages the directory entry to a fine grained directory such as a track level directory if the data does not satisfy the repository policy.

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: Disclosed is a system and program for task processing and monitoring of configuration and state information. A first server process and a second server process are detected. A first agent process is registered with the first server process. A second agent process is registered with the second server process. When a task is to be executed by the first server process, the task is executed with the first agent process. When the task is to be executed by the second server process, the task is executed with the second agent process.

Abstract: A method, system and computer program product for preserving data in a storage subsystem having dual cache and dual nonvolatile storage (NVS) through a failover from a failed cluster to a surviving cluster, the surviving cluster undergoing a rebooting process, is provided. A memory preserved indicator associated with a cache of the surviving cluster is detected. The memory preserved indicator designates marked tracks having an image in an NVS of the failed cluster to be preserved through the rebooting process. A counter in a data structure of the surviving cache is incremented. If a value of the counter exceeds a predetermined value, a cache memory is initialized, and the marked tracks are removed from the cache to prevent an instance of repetitive reboots caused by a corrupted structure in the cache memory.

Abstract: A system and method for controlling peer-to-peer remote copy (PPRC) operations initiated from one or more host devices that desire to store data contents written to a first storage system to a second storage system over a communications link. The system enables receipt and generation of copy services commands from host devices and the determination of whether a received command pertains to a copy service over an established PPRC relationship for that particular customer to enable that customer to perform storage operations effecting data written to a first storage server having source volumes and stored in a remote second storage system having target volumes. The copy services command effecting data contents of source volumes and/or remote target volumes will be enabled if it is determined that said PPRC relationship is already established for that customer; and, prevented if the received copy services command does effect any volume not already in a copy services relationship.

Abstract: A computational device allocates a plurality of solid state disks to a plurality of redundant array of independent disk (RAID) ranks, wherein a different solid state disk is absent in each RAID rank of the plurality of RAID ranks. The computational device determines at least one selected solid state disk from the plurality of solid state disks, wherein the at least one selected solid state disk is estimated to have undergone a greater amount of wear in comparison to other solid state disks in the plurality of solid state disks. Relatively more data and parity information is written to those RAID ranks in which the at least one selected solid state disk is absent in comparison to those RAID ranks in which the at least one selected solid state disk is present.

Abstract: A method to maintain write operation atomicity where a write operation crosses a data storage medium track boundary. The method supplies a storage controller comprising a host adapter, a processor, and a NVS. The primary host adapter receives from a host computer a write request and data. The method determines if the write request will cross a data storage medium track boundary. If the write request will cross a data storage medium track boundary, the method indicates to the host adapter that the write request comprises a two-track transfer, and writes the data to the primary NVS as the data is received. If the host computer fails prior to providing all the data to the storage controller, the method discards the data written to the NVS to ensure write operation atomicity.

Abstract: Provided are a system and article of manufacture, wherein in certain embodiments an I/O command from a host is received at a first storage unit. An identifier is generated that identifies a destination to which the I/O command is to be transmitted from the first storage unit. The I/O command is augmented with the generated identifier at the first storage unit. The augmented I/O command is transmitted. In certain other embodiments, an I/O command is received at a storage unit, wherein the storage unit is associated with a storage unit identifier. A determination is made at the storage unit, whether the I/O command is associated with an identifier that identifies a destination for which the I/O command is intended. A further determination is made, at the storage unit, whether the identifier is the same as the storage unit identifier, in response to determining that the identifier associated with the I/O command identifies the destination for which the I/O command is intended.

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 is a system, deployment and program for resource allocation unit queuing in which an allocation unit associated with a task is classified. An allocation unit freed as the task ends is queued for use by another task in a queue at a selected location within the queue in accordance with the classification of said allocation unit. In one embodiment, an allocation unit is queued at a first end of the queue if classified in a first class and is queued at a second end of the queue if classified in said second class. Other embodiments are described and claimed.

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 program for an adaptor to read and write to system memory. A plurality of blocks of data to write to storage are received at an adaptor. The blocks of data are added to a buffer in the adaptor. A determination is made of pages in a memory device and I/O requests are generated to write the blocks in the buffer to the determined pages, wherein two I/O requests are generated to write to one block split between two pages in the memory device. The adaptor executes the generated I/O requests to write the blocks in the buffer to the determined pages in the memory device.

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: An apparatus, system, and method are disclosed for copying data from a volatile memory device to a plurality of persistent storage devices in response to a loss of primary power. The apparatus includes a section module, a stripe module, and a write module. The section module sections a data image of a write cache into a plurality of data blocks. The stripe module establishes a plurality of data stripes from the plurality of data blocks. The write module writes in parallel each of the plurality of data stripes to a corresponding plurality of unique, persistent data storage devices in response to a loss of line power to the write cache. Advantageously, the apparatus quickly copies the write data from the write cache to a persistent memory device in a relatively short period of time, decreasing the dependence on significant batteries to back up the volatile memory device.

Abstract: Provided are a method, system, and article of manufacture, wherein a controller receives encrypted data from a first storage unit coupled to the controller. The received encrypted data is stored in a second storage unit coupled to the controller, wherein the controller is capable of accessing the second storage unit faster in comparison to the first storage unit. The encrypted data is maintained in the second storage unit, until at least one condition is satisfied.

Abstract: A method, system, and computer program product for grouping and dispatching scans in a cache directory of a processing environment is provided. A plurality of scan tasks is aggregated from a scan wait queue into a scan task queue. The plurality of scan tasks is determined by selecting one of (1) each of the plurality of scan tasks on the scan wait queue, (2) a predetermined number of the plurality of scan tasks on the scan wait queue, and (3) a set of scan tasks of a similar type on the scan wait queue. A first scan task from the plurality of scan tasks is selected from the scan task queue. The scan task is performed.

Abstract: Provided are a method, system, and article of manufacture for maintaining information of a relationship of target volumes comprising logical copies of a source volume. Information is maintained on a source volume having a plurality of data units and a plurality of target volumes created at different points-in-time maintaining a logical copy of the data units in the source volume for the different points-in-time. A source downstream pointer is generated for each data unit in the source volume to point to a corresponding data unit in a first target volume. For each target volume data unit whose data is maintained in the source volume or another one of the target volumes, a first upstream pointer is generated indicating one of the source and target volumes from which the target volume data unit inherits data.

Abstract: A method, system and computer program product for preserving data in a storage subsystem having dual cache and dual nonvolatile storage (NVS) through a failover from a failed cluster to a surviving cluster, the surviving cluster undergoing a rebooting process, is provided. A memory preserved indicator associated with a cache of the surviving cluster is detected. The memory preserved indicator designates marked tracks having an image in an NVS of the failed cluster to be preserved through the rebooting process. A counter in a data structure of the surviving cache is incremented. If a value of the counter exceeds a predetermined value, a cache memory is initialized, and the marked tracks are removed from the cache to prevent an instance of repetitive reboots caused by a corrupted structure in the cache memory.

Abstract: A method, system, and computer program product for preserving data in a storage subsystem having dual cache and dual nonvolatile storage (NVS) through a failover from a failed cluster to a surviving cluster is provided. A memory preserved indicator is initiated to mark tracks on a cache of the surviving cluster to be preserved, the tracks having an image in an NVS of the failed cluster. A destage operation is performed to destage the marked tracks. Subsequent to a determination that each of the marked tracks have been destaged, the memory preserved indicator is disabled to remove the mark from the tracks. If the surviving cluster reboots previous to each of the marked tracks having been destaged, the cache is verified as a memory preserved cache, the marked tracks are retained for processing while all unmarked tracks are removed, and the marked tracks are processed.