Abstract: A method to maintain write operation atomicity where a write operation crosses a data storage medium track boundary. The method supplies a storage controller comprising a host adapter, a processor, and a NVS. The host adapter receives from a host computer a write request and data. The method determines if the write request will cross a data storage medium track boundary. If the write request will cross a data storage medium track boundary, the method indicates to the host adapter that the write request comprises a two-track transfer, and writes the data to the NVS as the data is received. If the host computer fails prior to providing all the data to the storage controller, the method discards the data written to the NVS to ensure write operation atomicity.

Abstract: An apparatus, system, and method are disclosed for relocating logical array hot spots. An organization module organizes a plurality of logical arrays. Each logical array comprises a plurality of logical segments from a plurality of storage devices and configured to store data. An identification module identifies a hot spot on a first logical array if accesses to the first logical array exceed an access threshold. A migration module dynamically migrates a first logical segment from the first logical array to a second logical segment of a second logical array, wherein the migration is transparent to a host and data of the first logical segment is continuously available to the host.

Abstract: An apparatus, system, and method are disclosed for migrating wear spots in solid-state drives. A count module counts lifetime write cycles for logical units of a plurality of solid-state memories. Each logical unit has a logical address. An identification module identifies a wear spot on a first logical unit of a first solid-state memory if a count for the first logical unit exceeds a cycle threshold. A migration module dynamically migrates data of the first logical unit to a second solid-state memory, wherein the data is continuously available at an original logical address.

Abstract: A method, system, and computer program product for preserving data in a storage subsystem having dual cache and dual nonvolatile storage (NVS) through a failover from a failed cluster to a surviving cluster is provided. A memory preserved indicator is initiated to mark tracks on a cache of the surviving cluster to be preserved, the tracks having an image in an NVS of the failed cluster. A destage operation is performed to destage the marked tracks. Subsequent to a determination that each of the marked tracks have been destaged, the memory preserved indicator is disabled to remove the mark from the tracks. If the surviving cluster reboots previous to each of the marked tracks having been destaged, the cache is verified as a memory preserved cache, the marked tracks are retained for processing while all unmarked tracks are removed, and the marked tracks are processed.

Abstract: Non volatile storage may be employed to temporarily store data which is destaged to data storage drives. The non volatile storage is configured to preserve the data through a power outage. Some data may be preserved, but is not needed, such as the result of a failover to another non volatile storage. This unneeded data is tested to verify the non volatile storage by indicating whether the data survived the power cycle from full power to self refresh mode battery power to full power, without risking the loss of data that is needed.

Abstract: A method, system and computer program product for preserving data in a storage subsystem having dual cache and dual nonvolatile storage (NVS) through a failover from a failed cluster to a surviving cluster, the surviving cluster undergoing a rebooting process, is provided. A memory preserved indicator associated with a cache of the surviving cluster is detected. The memory preserved indicator designates marked tracks having an image in an NVS of the failed cluster to be preserved through the rebooting process. A counter in a data structure of the surviving cache is incremented. If a value of the counter exceeds a predetermined value, a cache memory is initialized, and the marked tracks are removed from the cache to prevent an instance of repetitive reboots caused by a corrupted structure in the cache memory.

Abstract: A method to maintain write operation atomicity where a write operation crosses a data storage medium track boundary. The method supplies a storage controller comprising a host adapter, a processor, and a NVS. The primary host adapter receives from a host computer a write request and data. The method determines if the write request will cross a data storage medium track boundary. If the write request will cross a data storage medium track boundary, the method indicates to the host adapter that the write request comprises a two-track transfer, and writes the data to the primary NVS as the data is received. If the host computer fails prior to providing all the data to the storage controller, the method discards the data written to the NVS to ensure write operation atomicity.

Abstract: An apparatus, system, and method are disclosed for data tracking and, in particular, for facilitating failure management within an electronic data communication system. The apparatus includes a tracking module and an error analysis module. The tracking module stores an adapter identifier in a tracking array. The adapter identifier corresponds to a source adapter from which data is received. The error analysis module determines a source of a data failure in response to recognition of the data failure. The data failure may occur on a host adapter, a device adapter, a communication fabric, a multi-processor, or another communication device. The apparatus, system, and method may be implemented in place of or in addition to hardware-assisted data integrity checking within a data storage system.

Abstract: Provided are a method, system, and program for managing write processes in which a list of destination location identifiers for pending write operations is maintained in an array having an array pointer which identifies the next available entry of the array. In one embodiment, the array includes a stack of variable size. Adding a destination location identifier of a pending write operation increases the size of the stack. Removing a destination location identifier of a completed write operation reduces the size of the stack. A stack index may be incremented as write operation destination location identifiers are added and may be decremented as write operation destination location identifiers are removed from the stack.

Abstract: Provided are a method, system, and article of manufacture for copying data from a first cluster to a second cluster to reassign storage areas from the first cluster to the second cluster. An operation is initiated to reassign storage areas from a first cluster to a second cluster, wherein the first cluster includes a first cache and a first storage unit and the second cluster includes a second cache and a second storage unit. Data in the first cache for the storage areas to reassign to the second cluster is copied to the second cache. Data in the first storage unit for storage areas remaining assigned to the first cluster is copied to the second storage unit.

Abstract: Provided are a method, system, and article of manufacture for determining modified data in cache for use during a recovery operation. An event is detected during which processing of writes to a storage device is suspended. A cache including modified data not destaged to the storage device is scanned to determine the data units having modified data in response to detecting the event. The data units having the modified data is indicated in a backup storage. The indication of the data units having the modified data in the backup storage is used during a recovery operation.

Abstract: In a data storage subsystem with disk storage and a pair of clusters, one set of DASD fast write data is in cache of one cluster and in non-volatile data storage of the other. In response to a failover of one of the pair of clusters to a local cluster, the local cluster converts the DASD fast write data in local cache to converted fast write data to prioritize the converted data for destaging to disk storage. In response to failure to destage, the local cluster allocates local non-volatile storage tracks and emulates a host adapter to store the converted fast write data by the local non-volatile storage, reconverting the converted fast write data of the non-volatile storage to local DASD fast write data stored in the local non-volatile storage and stored in the local cache storage.

Abstract: An apparatus, system, and method are disclosed for migrating wear spots in solid-state drives. A count module counts lifetime write cycles for logical units of a plurality of solid-state memories. Each logical unit has a logical address. An identification module identifies a wear spot on a first logical unit of a first solid-state memory if a count for the first logical unit exceeds a cycle threshold. A migration module dynamically migrates data of the first logical unit to a second solid-state memory, wherein the data is continuously available at an original logical address.

Abstract: A method, system, and computer program product for preserving data in a storage subsystem having dual cache and dual nonvolatile storage (NVS) through a failover from a failed cluster to a surviving cluster is provided. A memory preserved indicator is initiated to mark tracks on a cache of the surviving cluster to be preserved, the tracks having an image in an NVS of the failed cluster. A destage operation is performed to destage the marked tracks. Subsequent to a determination that each of the marked tracks have been destaged, the memory preserved indicator is disabled to remove the mark from the tracks. If the surviving cluster reboots previous to each of the marked tracks having been destaged, the cache is verified as a memory preserved cache, the marked tracks are retained for processing while all unmarked tracks are removed, and the marked tracks are processed.

Abstract: A method, system and computer program product for preserving data in a storage subsystem having dual cache and dual nonvolatile storage (NVS) through a failover from a failed cluster to a surviving cluster, the surviving cluster undergoing a rebooting process, is provided. A memory preserved indicator associated with a cache of the surviving cluster is detected. The memory preserved indicator designates marked tracks having an image in an NVS of the failed cluster to be preserved through the rebooting process. A counter in a data structure of the surviving cache is incremented. If a value of the counter exceeds a predetermined value, a cache memory is initialized, and the marked tracks are removed from the cache to prevent an instance of repetitive reboots caused by a corrupted structure in the cache memory.

Abstract: An apparatus, system, and method are disclosed for preventing write starvation in a storage controller with access to low performance storage devices. A storage device allocation module is included to assign a storage device write cache limit for each storage device accessible to a storage controller. The storage device write cache limit comprises a maximum amount of write cache of the storage controller available to a storage device for a write operation. At least one storage device comprises a low performance storage device and a total amount of storage available to the storage devices comprises an amount greater than a total storage capacity of the write cache. A low performance write cache limit module is included to set a low performance write cache limit. The low performance write cache limit comprises an amount of write cache available for use by the at least one low performance storage device for a write operation.

Abstract: An apparatus, system, and method are disclosed for relocating storage pool hot spots. An identification module identifies a hot spot on a first storage pool if accesses to the first storage pool exceed an access threshold. The first storage pool is part of a plurality of storage pools. Each storage pool comprises a plurality of logical segments from a plurality of storage devices. Each storage device is of a specified class. A migration module dynamically migrates data of a first logical segment to a second storage pool. The migration is transparent to a host and the data of the first logical segment is continuously available to the host.

Abstract: An apparatus, system, and method are disclosed for relocating logical array hot spots. An organization module organizes a plurality of logical arrays. Each logical array comprises a plurality of logical segments from a plurality of storage devices and configured to store data. An identification module identifies a hot spot on a first logical array if accesses to the first logical array exceed an access threshold. A migration module dynamically migrates a first logical segment from the first logical array to a second logical segment of a second logical array, wherein the migration is transparent to a host and data of the first logical segment is continuously available to the host.

Abstract: Provided are a method, system, and program for managing write processes in which a list of destination location identifiers for pending write operations is maintained in an array having an array pointer which identifies the next available entry of the array. In one embodiment, the array includes a stack of variable size. Adding a destination location identifier of a pending write operation increases the size of the stack. Removing a destination location identifier of a completed write operation reduces the size of the stack. A stack index may be incremented as write operation destination location identifiers are added and may be decremented as write operation destination location identifiers are removed from the stack.

Abstract: Provided are a method, system, and program for managing write processes in which a list of destination location identifiers for pending write operations is maintained in an array having an array pointer which identifies the next available entry of the array. In one embodiment, the array includes a stack of variable size. Adding a destination location identifier of a pending write operation increases the size of the stack. Removing a destination location identifier of a completed write operation reduces the size of the stack. A stack index may be incremented as write operation destination location identifiers are added and may be decremented as write operation destination location identifiers are removed from the stack.