A non-volatile storage system that is implementing a storage region (e.g., a persistent memory region) which is accessible to a host (e.g., via a PCIe connection) and a cache for the storage region shares details of the structure of the storage region and/or the cache (e.g., cache segment size). With awareness of the shared details of the structure of the storage region and/or the cache, the host arranges and sends out requests to read data from the persistent memory region in a manner that takes advantage of parallelism within the non-volatile storage system. For example, the host may initially send out one read request per cache segment to cause the non-volatile storage system to load the cache. Subsequently, additional read requests are made to the non-volatile storage system, with the data already loaded (or starting to load) in the cache, thereby increasing performance.

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.

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.

Provided are a computer program product, system, and method for determining tracks to prestage into cache from a storage. Information is provided related to determining tracks to prestage from the storage to the cache in a stage group of sequential tracks including a trigger track comprising a track number in the stage group at which to start prestaging tracks and Input/Output (I/O) activity information to a machine learning module. A new trigger track in the stage group at which to start prestaging tracks is received from the machine learning module having processed the provided information. The trigger track is set to the new trigger track. Tracks are prestaged in response to processing an access request to the trigger track in the stage group.

A method for improving destage performance to a RAID array is disclosed. In one embodiment, such a method periodically scans a cache for first strides that are ready to be destaged to a RAID array. While scanning the cache, the method identifies second strides that are not currently ready to be destaged to the RAID array, but will likely be ready to be destaged during a subsequent scan of the cache. The method initiates preemptive staging of any missing data of the second strides from the RAID array into the cache in preparation for the subsequent scan. Upon occurrence of the subsequent scan, the method destages, from the cache, the second strides from the cache to the RAID array. A corresponding system and computer program product are also disclosed.

In one embodiment, storage drive dependent track removal processing logic performs destage tasks for tracks cached in a cache as a function of whether the storage drive is classified as a fast class or as slow class of storage drives, for example. In one embodiment, a destage task configured for a slow class storage drive, transfers an entry for a track selected for destaging from a main cache list to a wait cache list to await destaging to the slow class drive. A destage task configured for a fast class storage drive allows the cache list entry for the selected track to remain on the main cache list while the selected track is being destaged to the fast class storage drive, thereby bypassing the transfer of the entry to a wait cache list. Other features and aspects may be realized, depending upon the particular application.

Aspects of the present disclosure relate to reducing the latency of data deduplication. In embodiments, an input/output (IO) workload received by a storage array is monitored. Further, at least one IO write operation in the IO workload is identified. A space-efficient probabilistic data structure is used to determine if a director board is associated with the IO write. Additionally, the IO write operation is processed based on the determination.

Provided are a computer program product, system, and method for invoking demote threads on processors to demote tracks from a cache. A plurality of demote ready lists indicate tracks eligible to demote from the cache. In response to determining that a number of free cache segments in the cache is below a free cache segment threshold, a determination is made of a number of demote threads to invoke on processors based on the number of free cache segments and the free cache segment threshold. The determined number of demote threads are invoked to demote tracks in the cache indicated in the demote ready lists, wherein each invoked demote thread processes one of the demote ready lists to select tracks to demote from the cache to free cache segments in the cache.

In one embodiment, storage drive dependent track removal processing logic performs destage tasks for tracks cached in a cache as a function of whether the storage drive is classified as a fast class or as slow class of storage drives, for example. In one embodiment, a destage task configured for a slow class storage drive, transfers an entry for a track selected for destaging from a main cache list to a wait cache list to await destaging to the slow class drive. A destage task configured for a fast class storage drive allows the cache list entry for the selected track to remain on the main cache list while the selected track is being destaged to the fast class storage drive, thereby bypassing the transfer of the entry to a wait cache list. Other features and aspects may be realized, depending upon the particular application.

A system includes a read/write module and a caching module. The read/write module is configured to access a first portion of a recording surface of a rotating storage device. Data is stored on the first portion of the recording surface of the rotating storage device at a first density. The caching module is configured to cache data on a second portion of the recording surface of the rotating storage device at a second density. The second portion of the recording surface of the rotating storage device is separate from the first portion of the recording surface of the rotating storage device. The second density is less than the first density.