Abstract: Provided are techniques for task adjustment for uniform performance of drives. Arrays are created for different drive types. Performance benchmarks are run for each of the arrays to compute a stage maximum value and a destage maximum value for each of the drive types. At run time, in response to determining that a mode indictor indicates a uniform performance mode, a maximum number of stage Task Control Blocks (TCBs) are set to a stage maximum uniform value and a maximum number of destage TCBs are set to a destage maximum uniform value. The stage of first data is performed using an actual number of stage TCBs that do not exceed the maximum number of stage TCBs. The destage of second data is performed using an actual number of destage TCBs that do not exceed the maximum number of destage TCBs.

Abstract: A computer-implemented method, according to one approach, includes: monitoring performance in NVRAM having a plurality of memory blocks. Moreover, a change in the flow rate of I/O requests received at the NVRAM is identified as a result of the monitoring. In response to identifying the change is an increase in the flow rate of received I/O requests, the percentage of invalid pages in a given block of NVRAM that triggers garbage collection to be performed on the given block is increased. However, in response to identifying the change is a decrease in the flow rate of received I/O requests, the percentage of invalid pages in a given block that triggers garbage collection to be performed on the given block is decreased.

Abstract: Provided are techniques for task adjustment for uniform performance of drives. Arrays are created for different drive types. Performance benchmarks are run for each of the arrays to compute a stage maximum value and a destage maximum value for each of the drive types. At run time, in response to determining that a mode indictor indicates a uniform performance mode, a maximum number of stage Task Control Blocks (TCBs) are set to a stage maximum uniform value and a maximum number of destage TCBs are set to a destage maximum uniform value. The stage of first data is performed using an actual number of stage TCBs that do not exceed the maximum number of stage TCBs. The destage of second data is performed using an actual number of destage TCBs that do not exceed the maximum number of destage TCBs.

Abstract: Provided are a computer program product, system, and method for determining a storage device type on which to store extents of data in a storage system. The storage system provides a first storage device type that has native data compression at a first compression ratio and a second storage device type that has native data compression at a second compression ratio. The second compression ratio is higher than the first compression ratio. A determination is made for an extent to store the extent on the first storage device type or the second storage device type based on access frequency to data in the extent and an Input/Output (I/O) priority level for the extent. The extent is stored on the determined first or second storage device type.

Abstract: Provided are a computer program product, system, and method for determining to migrate data between compressed storage devices and non-compressed storage devices in a storage system. The storage system provides compressed storage devices having native data compression and a non-compressed storage devices not configured to have native compression. A determination is made of storage usage factors for the compressed storage devices and the non-compressed storage devices. A determination is made whether to move data between the compressed storage devices and the non-compressed storage devices based on the storage usage factors. Data is moved between the compressed storage devices and the non-compressed storage devices in response to determining to move the data between the compressed storage devices and the non-compressed storage devices.

Abstract: Provided are a computer program product, system, and method for using a transient cache list and prolonged cache list to manage tracks in cache based on a demotion hint with a track access request. A track is staged into the cache in response to a request for the track. A determination is made as to whether the request provides a demotion hint. The track is indicated in a transient cache list in response to determining that the request provides the demotion hint. The track is indicated in a prolonged cache list in response to determining that the request does not provide the demotion hint. The track is demoted from the cache in response to the request for the track comprising a read request, returning the track to the read request, and the track is indicated in the transient cache list.

Abstract: Provided are a computer program product, system, and method for generating data protection directives to provide to a storage controller to control access to data in cache. A data protection directive is generated for a data subset indicating access request type and a protective action with respect to the access request type for the data subset. The data protection directive is transmitted to the storage controller. The storage controller includes the data protection directive in metadata for the data subset. The data protection directive causes the storage controller to perform the protective action in response to an access request of the access request type to a portion of the data subset.

Abstract: Provided are a computer program product, system, and method for processing data protection directives in metadata to determine whether to allow access to data in cache. A data protection directive is received, from the host, indicating a data subset, an access request type, and a protective action with respect to the access request type for the data subset. The data protection directive is stored in metadata for the data subset. In response to an access request to a requested data subset, determining a data protection directive in metadata for the requested data subset. Determining whether the access request comprises an access request type in the determined data protection directive. A protective action specified in the determined data protection directive is processed to determine whether to allow the access request access to the requested data subset in response to determining that the access request is of the access request type.

Abstract: Provided are a computer program product, system, and method for indicating extents of tracks in mirroring queues based on information gathered on tracks in extents in cache. Extent information on an extent of tracks in a cache indicated in an active cache list is processed in response to destaging a track from the active cache list to add to a demote list used to determine tracks to remove from the cache. The extent information is related to a number of modified tracks in an extent destaged from the active cache list. The extent information for the extent is used to determine one of a plurality of mirroring queues to indicate the extent including modified tracks. A mirroring queue having a higher priority than another mirroring queue is processed at a higher rate to determine extents of tracks to mirror from the cache to the secondary storage.

Abstract: Provided are a computer program product, system, and method for providing demotion hints with track access requests. A track access request is generated for a track in the storage system. A determination is made whether the track access request is for a designated utility. The track access request is submitted with a demotion hint to cause the track to be indicated on a transient cache list in response to determining that the track access request is for the designated utility. The track access request is submitted without a demotion hint in response to determining that the track access request is not for the designated utility to cause the track to be indicated on a prolonged cache list. The demotion of tracks is first attempted from the transient cache list before demoting tracks from the prolonged cache list.

Abstract: Provided are a computer program product, system, and method for using a transient cache list and prolonged cache list to manage tracks in cache based on a demotion hint with a track access request. A track is staged into the cache in response to a request for the track. A determination is made as to whether the request provides a demotion hint. The track is indicated in a transient cache list in response to determining that the request provides the demotion hint. The track is indicated in a prolonged cache list in response to determining that the request does not provide the demotion hint. The track is demoted from the cache in response to the request for the track comprising a read request, returning the track to the read request, and the track is indicated in the transient cache list.

Abstract: A computer-implemented method for managing tracks in a cache is provided. The computer-implemented method includes instantiating cache control blocks to each manage operations for one of the tracks and instantiating a bytemap corresponding to each of the cache control blocks. Each bytemap includes an active bit indicating whether the one of the tracks for which the corresponding cache control block manages operations is active and additional bits indicating additional characteristics of the one of the tracks for which the corresponding cache control block manages operations.

Abstract: In one general embodiment, a computer-implemented method includes detecting a thread attempting to acquire a TRY lock. A determination is made as to whether the thread has acquired the TRY lock. In response to the thread being unable to acquire the TRY lock within a predefined number of attempts to acquire the TRY lock, a number of attempts allowed is increased based on at least one predefined criterion. The thread is allowed to attempt to acquire a TRY lock within the increased number of attempts.

Abstract: Provided are a computer program product, system, and method for managing swappable data structures in a plurality of memory devices based on access counts of the data structures. Data structures indicated as swappable are updated less frequently than most frequently updated data structures. Data structures not indicated as swappable are maintained in a first level memory device and not moved to a second level memory device. The first level memory device has lower latency than the second level memory device. Access counts are maintained for the data structures stored in the first level memory device that are indicated as swappable. Data structures are selected in the first level memory device having lowest access counts. The selected data structures are removed from the first level memory device and retained in the second level memory device.

Abstract: Provided are a computer program product for managing tracks in a storage in a cache. An active track data structure indicates tracks in the cache that have an active status. An active bit in a cache control block for a track is set to indicate active for the track indicated as active in the active track data structure. In response to processing the cache control block, a determination is made, from the cache control block for the track, whether the track is active or inactive to determine processing for the cache control block.

Abstract: A computer-implemented method, according to one embodiment, includes: in response to a determination that an available capacity of one or more buffers in a primary cache is not outside a predetermined range, using the one or more buffers in the primary cache to satisfy all incoming I/O requests. In response to a determination that the available capacity of the one or more buffers in the primary cache is outside the predetermined range, one or more buffers in a secondary cache are allocated, and the one or more buffers in the secondary cache are used to satisfy at least some of the incoming I/O requests.

Abstract: Provided are I/O request type specific cache directories in accordance with the present description. In one embodiment, by limiting track entries of a cache directory to a specific I/O request type, the size of the cache directory may be reduced as compared to general cache directories for I/O requests of all types, for example. As a result, look-up operations directed to such smaller size I/O request type specific cache directories may be completed in each directory more quickly. In addition, look-ups may frequently be successfully completed after a look-up of a single I/O request type specific cache directory, improving the speed of cache look-ups and providing a significant improvement in system performance. Other aspects and advantages are provided, depending upon the particular application.

Abstract: In one aspect of write sort management in accordance with the present disclosure, a write sort task related to write sorting a write list of data units to be destaged to storage, is assigned to a storage controller to improve the load balance among plural storage controllers. In one embodiment, available processing capacities of each of the storage controllers is determined by, for example, polling each of the storage controllers. A write sort task may then be assigned to a selected storage controller as a function of determined available processing capacities of each of the storage controllers to improve the load balance among the storage controllers. Other aspects and advantages are provided, depending upon the particular application.

Abstract: Provided are a computer program product, system, and method for using track status information on active or inactive status of track to determine whether to process a host request on a fast access channel. A host request to access a target track is received on a first channel to the host. A determination is made as to whether the target track has active or inactive status. The target track has active status when at least one process currently maintains a lock on the target track that prevents access and the target track has inactive status when no process maintains a lock on the target track that prevents access. Fail is returned to the host to cause the host to resend the host request on a second channel in response to the target track having the active status. The first channel has lower latency than the second channel.

Abstract: Provided are a computer program product, system, and method for determining status of tracks in storage cached in a cache for a host. A storage controller receives from the host a list of tracks for the host to access and determines whether the tracks in the list are available in the cache for immediate access. A response is returned to the host indicating the tracks as one of available in the cache for immediate access and not available in the cache for immediate access.