摘要:
Provided are a computer program product, system, and method for processing a read operation for a target block of data. A read operation for the target block of data in target storage is received, wherein the target block of data is in an instant virtual copy relationship with a source block of data in source storage. It is determined that the target block of data in the target storage is not consistent with the source block of data in the source storage. The source block of data is retrieved. The data in the source block of data in the cache is synthesized to make the data appear to be retrieved from the target storage. The target block of data is marked as read from the source storage. In response to the read operation completing, the target block of data that was read from the source storage is demoted.
摘要:
Information on strides configured in the second cache includes information indicating a number of valid tracks in the strides, wherein a stride has at least one of valid tracks and free tracks not including valid data. A determination is made of tracks to demote from the first cache. A first stride is formed including the determined tracks to demote. The tracks from the first stride are added to a second stride in the second cache that has no valid tracks. A target stride in the second cache is selected based on a stride most recently used to consolidate strides from at least two strides into one stride. Data from the valid tracks is copied from at least two source strides in the second cache to the target stride.
摘要:
Provided are a computer program product, system, and method for managing track discard requests to include in discard track messages. A backup copy of a track in a cache is maintained in the cache backup device. A track discard request is generated to discard tracks in the cache backup device removed from the cache. Track discard requests are queued in a discard track queue. In response to detecting that a predetermined number of track discard requests are queued in the discard track queue while processing in a discard multi-track mode, one discard multiple tracks message is sent indicating the tracks indicated in the queued predetermined number of track discard requests to the cache backup device instructing the cache backup device to discard the tracks indicated in the discard multiple tracks message. In response to determining a predetermined number of periods of inactivity while processing in the discard multi-track mode, processing the track discard requests is switched to a discard single track mode.
摘要:
Provided are a computer program product, system, and method for caching data in a storage system having multiple caches. A sequential access storage device includes a sequential access storage medium and a non-volatile storage device integrated in the sequential access storage device, received modified tracks are cached in the non-volatile storage device, wherein the non-volatile storage device is a faster access device than the sequential access storage medium. A spatial index indicates the modified tracks in the non-volatile storage device in an ordering based on their physical location in the sequential access storage medium. The modified tracks are destaged from the non-volatile storage device by comparing a current position of a write head to physical locations of the modified tracks on the sequential access storage medium indicated in the spatial index to select a modified track to destage from the non-volatile storage device to the storage device.
摘要:
Provided a computer program product, system, and method for cache management of tracks in a first cache and a second cache for a storage. The first cache maintains modified and unmodified tracks in the storage subject to Input/Output (I/O) requests. Modified and unmodified tracks are demoted from the first cache. The modified and the unmodified tracks demoted from the first cache are promoted to the second cache. The unmodified tracks demoted from the second cache are discarded. The modified tracks in the second cache that are at proximate physical locations on the storage device are grouped and the grouped modified tracks are destaged from the second cache to the storage device.
摘要:
Provided are a computer program product, system, and method for prefetching data tracks and parity data to use for destaging updated tracks. A write request is received including at least one updated track to the group of tracks. The at least one updated track is stored in a first cache device. A prefetch request is sent to the at least one sequential access storage device to prefetch tracks in the group of tracks to a second cache device. A read request is generated to read the prefetch tracks following the sending of the prefetch request. The read prefetch tracks returned to the read request from the second cache device are stored in the first cache device. New parity data is calculated from the at least one updated track and the read prefetch tracks.
摘要:
Provided are a computer program product, sequential access storage device, and method for managing data in a sequential access storage device receiving read requests and write requests from a system with respect to tracks stored in a sequential access storage medium. A prefetch request indicates prefetch tracks in the sequential access storage medium to read from the sequential access storage medium. The accessed prefetch tracks are cached in a non-volatile storage device integrated with the sequential access storage device, wherein the non-volatile storage device is a faster access device than the sequential access storage medium. A read request is received for the prefetch tracks following the caching of the prefetch tracks, wherein the prefetch request is designated to be processed at a lower priority than the read request with respect to the sequential access storage medium. The prefetch tracks are returned from the non-volatile storage device to the read request.
摘要:
Provided are a computer program product, system, and method for using an attribute of a write request to determine where to cache data in a storage system having multiple caches including non-volatile storage cache in a sequential access storage device. Received modified tracks are cached in the non-volatile storage device integrated with the sequential access storage device in response to determining to cache the modified tracks. A write request having modified tracks is received. A determination is made as to whether an attribute of the received write request satisfies a condition. The received modified tracks for the write request are cached in the non-volatile storage device in response to determining that the determined attribute does not satisfy the condition. A destage request is added to a request queue for the received write request having the determined attribute not satisfying the condition.
摘要:
Exemplary system and computer program embodiments for storing data by a processor device in a computing environment are provided. In one embodiment, by way of example only, from a plurality of available data segments, a data segment having a storage activity lower than a predetermined threshold is identified as a colder data segment. A chunk of storage is located to which the colder data segment is assigned. The colder data segment is compressed. The colder data segment is migrated to the chunk of storage. A status of the chunk of storage is maintained in a compression data segment bitmap.
摘要:
Provided are a computer program product, system, and method for caching data in a storage system having multiple caches. A sequential access storage device includes a sequential access storage medium and a non-volatile storage device integrated in the sequential access storage device, received modified tracks are cached in the non-volatile storage device, wherein the non-volatile storage device is a faster access device than the sequential access storage medium. A spatial index indicates the modified tracks in the non-volatile storage device in an ordering based on their physical location in the sequential access storage medium. The modified tracks are destaged from the non-volatile storage device by comparing a current position of a write head to physical locations of the modified tracks on the sequential access storage medium indicated in the spatial index to select a modified track to destage from the non-volatile storage device to the storage device.