Abstract: A computer-implemented method, according to one approach, includes: initiating an I/O request using a primary cache, where the I/O request includes supplemental information pertaining to an anticipated workload of the I/O request. Performance characteristics experienced by the primary cache while satisfying the I/O request are also evaluated. The supplemental information and the performance characteristics are further used to determine whether to satisfy a remainder of the I/O request using the secondary cache. In response to determining to satisfy a remainder of the I/O request using the secondary cache, the I/O request is demoted from the primary cache to the secondary cache, and a remainder of the I/O request is satisfied using the secondary cache. However, in response to determining to not satisfy a remainder of the I/O request using the secondary cache, a remainder of the I/O request is satisfied using the primary cache.

Abstract: Provided are a computer program product, system, and method for prefetching cache resources for a write request from a host to tracks in storage cached in a cache. Cache resources held for a plurality of tracks in a write set are released before expected writes are received for the tracks in the write set. Cache resources for tracks in the write set are obtained, following the release of the cache resources, to use for expected write requests to the tracks in the write set.

Abstract: Provided are a computer program product, system, and method for providing track access reasons for track accesses resulting in the release of prefetched cache resources for the track. A first request for a track is received from a process for which prefetched cache resources to a cache are held for a second request for the track that is expected. A track access reason is provided for the first request specifying a reason for the first request. The prefetched cache resources are released before the second request to the track is received. Indication is made in an unexpected released track list of the track and the track access reason for the first request.

Abstract: Provided are a computer program product, system, and method for prefetching cache resources for a write request from a host to tracks in storage cached in a cache. Cache resources held for a plurality of tracks in a write set are released before expected writes are received for the tracks in the write set. Cache resources for tracks in the write set are obtained, following the release of the cache resources, to use for expected write requests to the tracks in the write set.

Abstract: Provided are a computer program product, system, and method for providing track access reasons for track accesses resulting in the release of prefetched cache resources for the track. A first request for a track is received from a process for which prefetched cache resources to a cache are held for a second request for the track that is expected. A track access reason is provided for the first request specifying a reason for the first request. The prefetched cache resources are released before the second request to the track is received. Indication is made in an unexpected released track list of the track and the track access reason for the first request.

Abstract: A computer-implemented method, according to one approach, includes: initiating an I/O request using a primary cache, where the I/O request includes supplemental information pertaining to an anticipated workload of the I/O request. Performance characteristics experienced by the primary cache while satisfying the I/O request are also evaluated. The supplemental information and the performance characteristics are further used to determine whether to satisfy a remainder of the I/O request using the secondary cache. In response to determining to satisfy a remainder of the I/O request using the secondary cache, the I/O request is demoted from the primary cache to the secondary cache, and a remainder of the I/O request is satisfied using the secondary cache. However, in response to determining to not satisfy a remainder of the I/O request using the secondary cache, a remainder of the I/O request is satisfied using the primary cache.

Abstract: A computer-implemented method, according to one approach, includes: receiving an I/O request which includes supplemental information pertaining to an anticipated workload of the I/O request. The supplemental information is used to determine whether to satisfy the I/O request using a primary cache. In response to determining to satisfy the I/O request using the primary cache, the I/O request is initiated using the primary cache, and performance characteristics experienced by the primary cache while satisfying the I/O request are evaluated. The supplemental information and the performance characteristics are further used to determine whether to satisfy a remainder of the I/O request using the secondary cache. In response to determining to satisfy a remainder of the I/O request using the secondary cache, the I/O request is demoted from the primary cache to the secondary cache, and a remainder of the I/O request is satisfied using the secondary cache.

Abstract: A method for performing a data exchange between an initiator and a receiver in a fiber channel protocol (FCP) is provided. A control flag is set in a write command to indicate the presence of an identifier. The identifier is copied into a command descriptor block (CDB) of the write command and appended to a data frame. The write command and data frame, including the identifier, is sent from the initiator to the receiver.

Abstract: A method for performing a data exchange between an initiator and a receiver in a fibre channel protocol (FCP) is provided. A control flag is set in a write command to indicate the presence of an identifier. The identifier is copied into a command descriptor block (CDB) of the write command and appended to a data frame. The write command and data frame, including the identifier, is sent from the initiator to the receiver.

Abstract: Provided are a method, system, and program monitoring paths between a first controller and second controller. A determination is made as to whether one path has been unavailable for a predetermined time period in response to detecting that the path is unavailable. Indication is made that the path is in a first failed state if the path has been unavailable for more than the predetermined time period and indication is made that the path is in a second failed state if the path has not been unavailable for the predetermined time period.

Abstract: Disclosed is a technique for assigning priorities. A request to manipulate data is received. A type of the request is determined. A priority is assigned to the request based on the type of the request.

Abstract: Provided are a method for monitoring paths between a first controller and second controller. A determination is made as to whether one path has been unavailable for a predetermined time period in response to detecting that the path is unavailable. Indication is made that the path is in a first failed state if the path has been unavailable for more than the predetermined time period and indication is made that the path is in a second failed state if the path has not been unavailable for the predetermined time period.

Abstract: Provided are a method, system, and program monitoring paths between a first controller and second controller. A determination is made as to whether one path has been unavailable for a predetermined time period in response to detecting that the path is unavailable. Indication is made that the path is in a first failed state if the path has been unavailable for more than the predetermined time period and indication is made that the path is in a second failed state if the path has not been unavailable for the predetermined time period.

Abstract: A method is disclosed to transfer information from a first information storage and retrieval system to a second information storage and retrieval system. The method provides a first information storage and retrieval system comprising a first track size and a plurality of first tracks, and a second information storage and retrieval system comprising a second track size and a plurality of second tracks. The method determines if the first track size is greater than the second track size. If the method determines that the first track size is greater than said second track size, then the method sets a ratio (R) equal to the first track size divided by the second track size, provides the (i)th first track from the first information storage and retrieval system to the second information storage and retrieval system, provides (R) second tracks, and maps the (i)th first track onto the (R) second tracks.

Abstract: Provided are a method, system, and program for copying tracks between a primary controller and secondary controller. A track is received from the primary controller that is part of a copy job comprising a sequence of tracks to copy along with a sequence number of the received track and a context number identifying computational resources in the primary controller used to transmit the track, sequence number, and context number. The context number and sequence number transmitted with the track are used to determine if a track preceding the received track was written to storage. The secondary-controller writes the received track to storage if the track preceding the received track was written to storage.

Abstract: Provided are a method, system, and program monitoring paths between a first controller and second controller. A determination is made as to whether one path has been unavailable for a predetermined time period in response to detecting that the path is unavailable. Indication is made that the path is in a first failed state if the path has been unavailable for more than the predetermined time period and indication is made that the path is in a second failed state if the path has not been unavailable for the predetermined time period.

Abstract: A method to provide information from a first information storage and retrieval system to a second information storage and retrieval system, where the first information storage and retrieval system comprises (N) PPRC adapters and information. The method generates and saves an Established Path Bitmap which recites the (N) PPRC adapters, and generates an Available Path Bitmap. If a PPRC adapter is in communication with the secondary storage system, then the method adds that adapter to the Available Path Bitmap. The primary information storage and retrieval system generates a PPRC task comprising a flag set to “off”. The method copies the Available Path Bitmap as a Working Bitmap, and generates a PPRC request comprising a flag set to “on”, selects one of the adapters recited in the Working Bitmap, and provides the PPRC request to that selected adapter. The method then once attempts to provide information to the second information storage and retrieval system using the selected adapter.

Abstract: A method is disclosed to transfer information from a first information storage and retrieval system to a second information storage and retrieval system. The method provides a first information storage and retrieval system comprising a first track size and a plurality of first tracks, and a second information storage and retrieval system comprising a second track size and a plurality of second tracks. The method determines if the first track size is greater than the second track size. If the method determines that the first track size is greater than said second track size, then the method sets a ratio (R) equal to the first track size divided by the second track size, provides the (i)th first track from the first information storage and retrieval system to the second information storage and retrieval system, provides (R) second tracks, and maps the (i)th first track onto the (R) second tracks.