Integration of the frequency of usage of tracks in a tiered storage system into a cache management system of a storage controller
First Claim
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1. A method, comprising:
- maintaining, by a cache management application, a cache for a storage controller and a list corresponding to tracks in the cache, wherein the cache management application places tracks in the list by measuring frequency of usage of tracks in a first time period;
maintaining, by a storage tier management application, a plurality of storage tiers controlled by the storage controller, wherein the storage tier management application collects usage statistics of tracks over a second time period;
maintaining, by the cache management application, in the list, a plurality of partitions, wherein each partition of the plurality of partitions is comprised of a plurality of tracks, and wherein each partition of the plurality of partitions represents a heat index range;
adding, by the cache management application, a new track to the list by;
determining a heat index of the new track as indicated by the storage tier management application; and
including the new track in a partition of the plurality of partitions whose heat index range encompasses the heat index of the new track; and
demoting, by the cache management application, a track from the list to discard the track from the cache by;
determining which partition of the plurality of partitions has a heat index range that encompasses lowest heat indexes;
determining whether the determined partition has one or more tracks;
in response to determining that the determined partition has one or more tracks, demoting a least recently used (LRU) track of the determined partition; and
in response to determining that the determined partition does not have one or more tracks, determining a new partition of the plurality of partitions that has a heat index range that encompasses next lowest heat indexes for demoting one or more additional tracks from the list.
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Abstract
A storage tier management application indicates a heat index for each extent of a plurality of extents, wherein a higher heat index indicates a greater frequency of usage of tracks of an extent than a lower heat index. A least recently used (LRU) list for cache management is configured to perform demotion of tracks of a lower heat index prior to demotion of tracks of a higher heat index.
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Citations
18 Claims
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1. A method, comprising:
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maintaining, by a cache management application, a cache for a storage controller and a list corresponding to tracks in the cache, wherein the cache management application places tracks in the list by measuring frequency of usage of tracks in a first time period; maintaining, by a storage tier management application, a plurality of storage tiers controlled by the storage controller, wherein the storage tier management application collects usage statistics of tracks over a second time period; maintaining, by the cache management application, in the list, a plurality of partitions, wherein each partition of the plurality of partitions is comprised of a plurality of tracks, and wherein each partition of the plurality of partitions represents a heat index range; adding, by the cache management application, a new track to the list by; determining a heat index of the new track as indicated by the storage tier management application; and including the new track in a partition of the plurality of partitions whose heat index range encompasses the heat index of the new track; and demoting, by the cache management application, a track from the list to discard the track from the cache by; determining which partition of the plurality of partitions has a heat index range that encompasses lowest heat indexes; determining whether the determined partition has one or more tracks; in response to determining that the determined partition has one or more tracks, demoting a least recently used (LRU) track of the determined partition; and in response to determining that the determined partition does not have one or more tracks, determining a new partition of the plurality of partitions that has a heat index range that encompasses next lowest heat indexes for demoting one or more additional tracks from the list. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A system, comprising:
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a memory; and a processor coupled to the memory, wherein the processor performs operations, the operations performed by the processor comprising; maintaining, by a cache management application, a cache and a list corresponding to tracks in the cache, wherein the cache management application places tracks in the list by measuring frequency of usage of tracks in a first time period; maintaining, by a storage tier management application, a plurality of storage tiers, wherein the storage tier management application collects usage statistics of tracks over a second time period; maintaining, by the cache management application, in the list, a plurality of partitions, wherein each partition of the plurality of partitions is comprised of a plurality of tracks, and wherein each partition of the plurality of partitions represents a heat index range; adding, by the cache management application, a new track to the list by; determining a heat index of the new track as indicated by the storage tier management application; and including the new track in a partition of the plurality of partitions whose heat index range encompasses the heat index of the new track; and demoting, by the cache management application, a track from the list to discard the track from the cache by; determining which partition of the plurality of partitions has a heat index range that encompasses lowest heat indexes; determining whether the determined partition has one or more tracks; in response to determining that the determined partition has one or more tracks, demoting a least recently used (LRU) track of the determined partition; and in response to determining that the determined partition does not have one or more tracks, determining a new partition of the plurality of partitions that has a heat index range that encompasses next lowest heat indexes for demoting one or more additional tracks from the list. - View Dependent Claims (8, 9, 10, 11, 12)
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13. A computer program product, the computer program product comprising a non-transitory computer readable storage medium having computer readable program code embodied therewith, the computer readable program code configured to perform operations, the operations comprising:
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maintaining, by a cache management application, a cache for a storage controller and a list corresponding to tracks in the cache, wherein the cache management application places tracks in the list by measuring frequency of usage of tracks in a first time period; maintaining, by a storage tier management application, a plurality of storage tiers controlled by the storage controller, wherein the storage tier management application collects usage statistics of tracks over a second time period; maintaining, by the cache management application, in the list, a plurality of partitions, wherein each partition of the plurality of partitions is comprised of a plurality of tracks, and wherein each partition of the plurality of partitions represents a heat index range; adding, by the cache management application, a new track to the list by; determining a heat index of the new track as indicated by the storage tier management application; and including the new track in a partition of the plurality of partitions whose heat index range encompasses the heat index of the new track; and demoting, by the cache management application, a track from the list to discard the track from the cache by; determining which partition of the plurality of partitions has a heat index range that encompasses lowest heat indexes; determining whether the determined partition has one or more tracks; in response to determining that the determined partition has one or more tracks, demoting a least recently used (LRU) track of the determined partition; and in response to determining that the determined partition does not have one or more tracks, determining a new partition of the plurality of partitions that has a heat index range that encompasses next lowest heat indexes for demoting one or more additional tracks from the list. - View Dependent Claims (14, 15, 16, 17, 18)
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Specification