Considering a density of tracks to destage in groups of tracks to select groups of tracks to destage
AssigneeInternational Business Machines Corporation
InventorsKevin J. Ash, Lokesh M. Gupta
Life of this patent
Estimating the term…
Abstract
Provided are a computer program product, system, and method for considering a density of tracks to destage in groups of tracks to select groups of tracks to destage. Groups of tracks in the cache are scanned to determine whether they are ready to destage. A determination is made as to whether the tracks in one of the groups are ready to destage in response to scanning the tracks in the group. A density for the group is increased in response to determining that the group is not ready to destage. The group is destaged in response to determining that the density of the group exceeds a density threshold.
Claims20
A computer program product for selecting tracks to destage from a cache to a storage, the computer program product comprising a computer readable storage medium having computer readable program code embodied therein that when executed performs operations, the operations comprising:
- scanning groups of tracks in the cache to determine whether they are ready to destage;
- determining whether the tracks in a group of tracks of the groups of tracks are ready to destage in response to scanning the tracks in the group of tracks;
- increasing a density for the group of tracks in response to determining that the group of tracks is not ready to destage;
- determining an urgency for destaging data based on an amount of available space in the cache, comprising one of a high urgency, medium urgency or low urgency;
- destaging the groups of tracks having the density greater than a mean of densities of the groups of tracks plus a standard deviation of the mean in response to determining the urgency comprises the low urgency;
- destaging the groups of tracks having the density greater than the mean in response to determining the urgency comprises the medium urgency;
- and
- destaging the groups of tracks having the density greater than the mean minus the standard deviation in response to determining the urgency comprises the high urgency.
A system in communication with a storage, comprising:
- a processor;
- a cache;
- and
- a computer readable storage medium having computer program code that when executed by the processor perform operations, the operations comprising:
- scanning groups of tracks in the cache to determine whether they are ready to destage;
- determining whether the tracks in a group of tracks of the groups of tracks are ready to destage in response to scanning the tracks in the group of tracks;
- increasing a density for the group of tracks in response to determining that the group of tracks is not ready to destage;
- determining an urgency for destaging data based on an amount of available space in the cache, comprising one of a high urgency, medium urgency or low urgency;
- destaging the groups of tracks having the density greater than a mean of densities of the groups of tracks plus a standard deviation of the mean in response to determining the urgency comprises the low urgency;
- destaging the groups of tracks having the density greater than the mean in response to determining the urgency comprises the medium urgency;
- and
- destaging the groups of tracks having the density greater than the mean minus the standard deviation in response to determining the urgency comprises the high urgency.
A method for selecting tracks to destage from a cache to a storage, comprising:
- scanning groups of tracks in the cache to determine whether they are ready to destage;
- determining whether the tracks in a group of tracks of the groups of tracks are ready to destage in response to scanning the tracks in the group of tracks;
- increasing a density for the group of tracks in response to determining that the group of tracks is not ready to destage;
- and
- determining an urgency for destaging data based on an amount of available space in the cache, comprising one of a high urgency, medium urgency or low urgency;
- destaging the groups of tracks having the density greater than a mean of densities of the groups of tracks plus a standard deviation of the mean in response to determining the urgency comprises the low urgency;
- destaging the groups of tracks having the density greater than the mean in response to determining the urgency comprises the medium urgency;
- and
- destaging the groups of tracks having the density greater than the mean minus the standard deviation in response to determining the urgency comprises the high urgency.
Dependencies are inferred from the claim text.