Abstract: Provided are a computer program product, system, and method for mirroring information on modified data from a primary storage controller to a secondary storage controller for the secondary storage controller to use to calculate parity data. New primary parity data is calculated from modified data for a primary group of tracks in the primary storage and difference data from the modified data and a pre-modified version of the modified data. The difference data and one of the modified data and the new primary parity data are sent to the secondary storage controller to cause the secondary storage controller to write new secondary parity data and the modified data to a secondary group of tracks at the secondary storage. The modified data and the new primary parity data are written to the primary group of tracks in the primary storage.

Abstract: Provided are a computer program product, system, and method for updating a track format table used to provide track format codes for cache control blocks with more frequently accessed track format metadata. A track format table associates track format codes with track format metadata. Each instance of the track format metadata indicates a layout of data in a track. Cache control blocks for tracks in the cache include track format codes associated with the track format metadata of the tracks in the cache. Track format access information indicating accesses of track format metadata not included in the track format table. Track format metadata, indicated in the track format access information that is not in the track format table, is added to the track format table to associate with a track format code based on a number of accesses of the track format metadata indicated in the track format access information.

Abstract: A method for dynamically altering the performance class of multiple storage drives is disclosed. In one embodiment, such a method monitors, within a storage environment, characteristics (e.g., age, wear, etc.) of multiple storage drives. Each storage drive has a performance class associated therewith. Based on the characteristics, the method periodically modifies the performance class of the storage drives. The method then reorganizes the storage drives within various storage groups (e.g., RAID arrays, storage tiers, workloads, etc.) based on their performance class. For example, the method may place, as much as possible, storage drives of the same performance class within the same storage groups. A corresponding system and computer program product are also disclosed.

Abstract: A method for dynamically altering logical storage capacity within multiple storage drives is disclosed. In one embodiment, such a method monitors, within a storage environment, characteristics (e.g., age, wear, etc.) of multiple storage drives. Each storage drive has an amount of overprovisioning associated therewith. Based on the characteristics, the method periodically modifies a logical storage capacity of the storage drives in order to alter the amount of overprovisioning. The method then reorganizes the storage drives within various storage groups (e.g., RAID arrays, storage tiers, workloads, etc.) based on their logical storage capacity. For example, the method may place, as much as possible, storage drives of the same logical storage capacity within the same storage groups. A corresponding system and computer program product are also disclosed.

Abstract: A method for dynamically altering a writes-per-day classification of multiple storage drives is disclosed. In one embodiment, such a method monitors, within a storage environment, an amount of overprovisioning utilized by multiple storage drives. Each storage drive has a writes-per-day classification associated therewith. Based on the amount of overprovisioning, the method periodically modifies the writes-per-day classification of the storage drives. The method then reorganizes the storage drives within various storage groups (e.g., RAID arrays, storage tiers, workloads, etc.) based on their writes-per-day classification. For example, the method may place, as much as possible, storage drives of the same writes-per-day classification within the same storage groups. A corresponding system and computer program product are also disclosed.

Abstract: A method for converting a redundant array of independent disks (RAID) to a more robust RAID level is disclosed. Such a method identifies, in a data storage environment, higher risk storage drives having a failure risk above a first threshold. The method determines a number of the higher risk storage drives that are contained within a RAID array of the data storage environment. The method determines whether the number exceeds a second threshold. The method also determines whether a destage rate associated with the RAID array is below a third threshold. In the event the number exceeds the second threshold and the destage rate is below the third threshold, the method converts the RAID array to a more robust RAID level. A corresponding system and computer program product are also disclosed.

Abstract: A method for reducing incidents of data loss in RAIDs of differing RAID levels is disclosed. Such a method identifies, in a data storage environment, first and second sets of RAIDs. The first set contains RAIDs providing more robust data protection (e.g., RAID-6 arrays), and the second set contains RAIDs providing less robust data protection (e.g., RAID-5 arrays). The method identifies, in the data storage environment, higher risk storage drives having a failure risk above a threshold and lower risk storage drives having a failure risk below the threshold. The method swaps higher risk storage drives from RAIDs of the second set with lower risk storage drives from RAIDs of the first set. In certain embodiments, the swapping may be performed such that no RAID of the second set includes more than a selected number of higher risk storage drives. A corresponding system and computer program product are also disclosed.

Abstract: A method for reporting incidents of data loss in a storage environment comprising redundant arrays of independent disks (RAIDs) is disclosed. In one embodiment, such a method monitors storage drive failures in a storage environment. For a storage drive failure detected in the storage environment, the method reports the RAID type in which the storage drive failure occurred and whether data loss occurred in the RAID as a result of the storage drive failure. In certain embodiments, the method reports whether the data loss could have been prevented had the RAID type been converted to a more robust RAID type. In other or the same embodiments, the method reports whether the data loss was prevented by the RAID type. A corresponding system and computer program product are also disclosed.

Abstract: A method for reducing incidents of data loss in redundant arrays of independent disks (RAIDs) having the same RAID level is disclosed. In one embodiment, such a method identifies, in a data storage environment, a set of RAIDs having a common RAID level. The method also identifies, in the set of RAIDs, higher risk storage drives having a failure risk above a threshold and lower risk storage drives having a failure risk below the threshold. The method swaps, within the RAIDs, higher risk storage drives with lower risk storage drives to more evenly distribute higher risk storage drives across the RAIDs. A corresponding system and computer program product are also disclosed.

Abstract: A method for invalidating a track of data on a storage drive in preparation to unpin the track is disclosed. In one embodiment, such a method includes invalidating certain metadata associated with a track of data residing on a storage drive of a storage system. The method further creates, in cache of the storage system, an invalid track image associated with the track. The method destages, from the cache, the invalid track image to the storage drive. Once the invalid track image is destaged, the method may unpin the track in cache, thereby enabling destages of the track from the cache to the storage drive going forward. A corresponding system and computer program product are also disclosed.

Abstract: A method for reclaiming storage space in RAID arrays made up of heterogeneous storage drives is disclosed. In one embodiment, such a method includes determining a most common storage capacity for a set of storage drives utilized in a storage system. The method further identifies physical storage drives from the set that contain unused storage space. The method pools the unused storage space of the physical storage drives to create virtual storage drives with storage capacities substantially equal to the most common storage capacity. The method then utilizes the virtual storage drives in existing or new RAID arrays. A corresponding system and computer program product are also disclosed.

Abstract: Provided are a computer program product, system, and method for managing cache segments between a global queue and a plurality of local queues using a machine learning module. Cache segment management information related to management of segments in the local queues and accesses to the global queue to transfer cache segments between the local queues and the global queue, are provided to a machine learning module to output an optimum number parameter comprising an optimum number of segments to maintain in a local queue and a transfer number parameter comprising a number of cache segments to transfer between a local queue and the global queue. The optimum number parameter and the transfer number parameter are sent to a processing unit having a local queue to cause the processing unit to transfer the transfer number parameter of cache segments between the local queue to the global queue.

Abstract: Provided are a computer program product, system, and method for managing cache segments between a global queue and a plurality of local queues by training a machine learning module. A machine learning module is provided input comprising cache segment management information related to management of segments in the local queues by the processing units and accesses of the global queue to transfer cache segments between the local queues and the global queue to output an optimum number parameter comprising an optimum number of segments to maintain in a local queue and a transfer number parameter comprising a number of cache segments to move between a local queue and the global queue. The machine learning module is retrained based on the cache segment management information to output an adjusted transfer number parameter and an adjusted optimum number parameter for the processing units.

Abstract: Provided are a computer program product, system, and method for populating a secondary cache with unmodified tracks in a primary cache when redirecting host access from a primary server to a secondary server. Host access to tracks is redirected from the primary server to the secondary server. Prior to the redirecting, updates to tracks in the primary storage were replicated to the secondary server. After the redirecting host access to the secondary server, host access is directed to the secondary server and the secondary storage. A secondary cache at the secondary server is populated with unmodified tracks in a primary cache at the primary server when the host access was redirected to the secondary server to make available to the host access redirected to the secondary server.

Abstract: A method for improving cache hit ratios for selected volumes within a storage system includes monitoring I/O to multiple volumes residing on a storage system. The method determines, from the I/O, which particular volumes of the multiple volumes would benefit the most if provided favored status in cache of the storage system, where the favored status provides increased residency time in the cache compared to volumes not having the favored status. The method determines, from the I/O, an amount by which the increased residency time should exceed a residency time of volumes not having the favored status. The method generates an indicator that is representative of the amount and transmits this indicator to the storage system. The storage system, in turn, provides increased residency time to the particular volumes in accordance with the favored status and indicator. A corresponding system and computer program product are also disclosed.

Abstract: A method for improving cache hit ratios for selected volumes within a storage system is disclosed. In one embodiment, such a method includes storing, in a cache of a storage system, non-favored storage elements and favored storage elements. The favored storage elements are retained in the cache longer than the non-favored storage elements. The method maintains a “non-favored” LRU list that contains entries associated with non-favored storage elements and designates an order in which the non-favored storage elements are evicted from the cache. The method also maintains one or more “favored” LRU lists that contain entries associated with favored storage elements and designate an order in which the favored storage elements are evicted from the cache. Each “favored” LRU list is associated with favored storage elements that have a different preferred residency time in the cache. A corresponding system and computer program product are also disclosed.

Abstract: A method for improving cache hit ratios for selected volumes when using synchronous I/O is disclosed. In one embodiment, such a method includes establishing, in cache, a first set of non-favored storage elements from non-favored storage areas. The method further establishes, in the cache, a second set of favored storage elements from favored storage areas. The method calculates a life expectancy for the non-favored storage elements to reside in the cache prior to eviction. The method further executes an eviction policy for the cache wherein the favored storage elements are maintained in the cache for longer than the life expectancy of the non-favored storage elements. A corresponding system and computer program product are also disclosed.

Abstract: A method for improving cache hit ratios for selected storage elements within a storage system is disclosed. In one embodiment, such a method includes storing, in a cache of a storage system, non-favored storage elements and favored storage elements. The favored storage elements are retained in the cache longer than the non-favored storage elements. The method maintains a first LRU list containing entries associated with non-favored storage elements and designating an order in which the non-favored storage elements are evicted from the cache, and a second LRU list containing entries associated with favored storage elements and designating an order in which the favored storage elements are evicted from the cache. The method moves entries between the first LRU list and the second LRU list as favored storage elements are changed to non-favored storage elements and vice versa. A corresponding system and computer program product are also disclosed.

Abstract: A method for improving cache hit ratios for selected volumes within a storage system is disclosed. In one embodiment, such a method includes monitoring I/O to multiple volumes residing on a storage system. The storage system includes a cache to store data associated with the volumes. The method determines, from the I/O, which particular volumes of the multiple volumes would benefit the most if provided favored status in the cache. The favored status provides increased residency time in the cache to the particular volumes compared to volumes not having the favored status. The method generates a list of the particular volumes and transmits the list to the storage system. The storage system, in turn, provides increased residency time to the particular volumes in accordance with their favored status. A corresponding system and computer program product are also disclosed.

Abstract: A computational device determines whether one or more tasks are waiting for accessing a cache for more than a predetermined amount of time while least recently used (LRU) based replacement of tracks are being performed for the cache via demotion of tracks from a LRU list of tracks corresponding to the cache. In response to determining that one or more tasks are waiting for accessing the cache for more than the predetermined amount of time, in addition to continuing to demote tracks from the LRU list, a plurality of deadlock prevention demotion tasks demote tracks from the cache.