Abstract: Method and system are provided for handling an underperforming drive in a redundant array of independent disks (RAID) operating a distributed sparing mechanism. The method includes marking an underperforming drive in the array as resting and allocating distributed spare space of the array for data of operations to the resting drive. A data structure is designated to track operations diverted to the distributed spare space from the resting drive. If the resting drive is recovered, the method rebuilds data to the recovered drive from the distributed spare space by reference to the data structure.

Abstract: Method and system are provided for handling an underperforming drive in a redundant array of independent disks (RAID) operating a distributed sparing mechanism. The method includes marking an underperforming drive in the array as resting and allocating distributed spare space of the array for data of operations to the resting drive. A data structure is designated to track operations diverted to the distributed spare space from the resting drive. If the resting drive is recovered, the method rebuilds data to the recovered drive from the distributed spare space by reference to the data structure.

Abstract: Illustrative embodiments provide a computer implemented method for incremental storage de-allocation during a clean process within a point-in-time copy storage management system. The computer implemented method determines whether to perform the clean process and responsive to a determination to perform the clean process, determines whether a set of discrepant bits is present. Responsive to the determination that the set of discrepant bits is present, the computer implemented method copies each dirty grain for each discrepant bit in the set of discrepant bits to a downstream target to form a set of copied dirty grains and determines whether a particular dirty grain in the set of copied dirty grains has been allocated to a space efficient storage unit. Responsive to a determination that the particular dirty grain was allocated to a space efficient storage unit, the computer implemented method de-allocates the particular grain from an upstream source.

Abstract: An apparatus, method, and computer program for facilitating disaster recovery of a first computer system, wherein first data residing on a first storage device associated with the first computer system is recoverable from second data residing on a second storage device associated with a second computer system and wherein the second storage device is operable to have an associated state of powered up or powered down. A receiver receives an update operation for updating the second storage device. A processor updates a non-volatile storage means with the update operation, prior to update of the second storage device, wherein the non-volatile storage means is associated with the second computer system.

Abstract: A storage controller includes an interface to host computer apparatus and an interface to a plurality of controlled storage apparatus. The storage controller comprises a host write component operable to send a request to write a data object to a source data image at one of said plurality of controlled storage apparatus; a copy component operable in response to a metadata state to control copying of said data object to a target data image in a delimited sequence of data images in a cascade at said plurality of controlled storage apparatus and a fill-in component operable in response to detection of an offline condition of a disk containing said target data image to control substitution of a fill-in disk in place of said disk containing said target data image.

Abstract: Illustrative embodiments provide a computer implemented method for incremental storage de-allocation during a clean process within a point-in-time copy storage management system. The computer implemented method determines whether to perform the clean process and responsive to a determination to perform the clean process, determines whether a set of discrepant bits is present. Responsive to the determination that the set of discrepant bits is present, the computer implemented method copies each dirty grain for each discrepant bit in the set of discrepant bits to a downstream target to form a set of copied dirty grains and determines whether a particular dirty grain in the set of copied dirty grains has been allocated to a space efficient storage unit. Responsive to a determination that the particular dirty grain was allocated to a space efficient storage unit, the computer implemented method de-allocates the particular grain from an upstream source.

Abstract: A storage controller includes an interface to host computer apparatus and an interface to a plurality of controlled storage apparatus. The storage controller comprises a host write component operable to send a request to write a data object to a source data image at one of said plurality of controlled storage apparatus; a copy component operable in response to a metadata state to control copying of said data object to a target data image in a delimited sequence of data images in a cascade at said plurality of controlled storage apparatus and a fill-in component operable in response to detection of an offline condition of a disk containing said target data image to control substitution of a fill-in disk in place of said disk containing said target data image.

Abstract: A storage controller includes an interface to host computer apparatus and an interface to a plurality of controlled storage apparatus. The storage controller comprises a host write component operable to send a request to write a data object to a source data image at one of said plurality of controlled storage apparatus; a copy component operable in response to a metadata state to control copying of said data object to a target data image in a delimited sequence of data images in a cascade at said plurality of controlled storage apparatus and a fill-in component operable in response to detection of an offline condition of a disk containing said target data image to control substitution of a fill-in disk in place of said disk containing said target data image.