Abstract: In one embodiment, a system includes a storage subsystem having an array of storage devices; a receiving component for receiving an error message; a determining component for determining that the error message indicates that a storage device has failed; a collecting component for collecting an array record having storage device characteristics of the failed storage device; a collating component for collating a candidate record having a plurality of candidate entries; a comparing component for comparing storage device characteristics of the failed storage device of the array record with the storage device characteristics of each of the candidate entries; and an identifying component for identifying a first candidate storage device having storage device characteristics that match the storage device characteristics of the failed storage device or a second candidate storage device having storage device characteristics most similar to the storage device characteristics of the failed storage device.

Abstract: Provided are a method, system, and a computer program product handling a backup process. An instruction is received initiating a new backup from a source volume to a target volume using one of a plurality of backup processes. A determination is made as to whether there is a cascade of volumes using the backup process including the source volume of the new backup. The cascade includes a cascade source volume and at least one cascade target volume, and a write to a storage location in one of the cascade volumes causes a copying of the storage location to be written in the cascade source volume to each of the cascade target volumes in the cascade according to a cascade order in which the at least one cascade target volume and the cascade source volume are linked in the cascade. The cascade, using the backup process of the new backup already including the source volume of the new backup, is modified to include the target volume of the new backup in response to determining that there is the existing cascade.

Abstract: Methods and systems for memory management. A method for memory management includes: maintaining a reference count for at least one first process associated with a portion of memory; maintaining a shared reference count for at least one second process associated with the portion of memory; and freeing the portion of memory when the shared reference count is decremented to zero.

Abstract: An apparatus or method for operating a mirrored disk storage system, comprises a detector component operable to detect that a failure has left read stability in doubt, a determiner component for determining a repair characteristic of a pair of mirrored disks, a comparator for comparing the repair characteristic of a first of the pair with the repair characteristic of a second of the pair, and a selector for selecting one of the first or the second of the pair having a preferred repair characteristic to be used as a synchronization source disk. The preferred repair characteristic comprises the characteristic that no repair is required for the one of the first or the second of the pair, or that a least repair time is required for the one of the first or the second of the pair.

Abstract: A technique for handling a FlashCopy® process includes receiving a FlashCopy® instruction for a source disk, performing a FlashCopy® point in time copy of the source disk on to a target disk, creating a map specifying the FlashCopy® point in time copy from the source disk to the target disk, creating a primary fdisk for the source disk, if one does not already exist, and creating a primary fdisk for the target disk, if one does not already exist, or, if one does already exist, converting the existing primary fdisk for the target disk into a secondary fdisk, and creating a new primary fdisk for the target disk.

Abstract: A method for migrating data between heterogeneous data storage devices within a storage area network is disclosed. A first virtualizer presents stored data as a first virtual disk, and then communicates a managed disk representation of the first virtual disk to a second virtualizer. After receiving the managed disk representation, the second virtualizer virtualizes the stored data from the managed disk representation as a second virtual disk. At such point, the stored data can be progressively migrated from the first virtualizer to the second virtualizer.

Abstract: An apparatus for real-time performance management of a virtualized storage system operable in a network having managed physical storage and virtual storage presented by an in-band virtualization controller comprises: a monitoring component operable in communication with the network for acquiring performance data from the managed physical storage and the virtual storage; and a cache controller component responsive to the monitoring component for adjusting cache parameters for the virtual storage. The apparatus may further comprise a queue controller component responsive to the monitoring component for adjusting queue parameters for the managed physical storage. The monitoring component, the cache controller component and the queue controller component may be configured to operate periodically during operation of the virtualized storage system.

Abstract: A backup control apparatus for periodic data backup, in a virtualized storage system having a point-in-time copy function operable to copy first data into a cascade, comprises a storage targeting component for selecting a target virtual disk for one of a full copy or an incremental copy of the first data; a periodic backup component for triggering a periodic point-in-time copy of the first data to a virtual disk in the cascade; a testing component for testing a status of the full copy, the incremental copy and the periodic point-in-time copy; and a cascade splitting component responsive to the status for splitting the cascade to remove a dependency relationship of at least one of the full copy, the incremental copy and the periodic point-in-time copy on the first data.

Abstract: This invention relates to a method, system and computer program product for reading data from a storage controller in storage area network. A read data instruction is received from an application requesting data from the storage controller using a primary data path. If the data on the primary data path is not transferred in a defined time interval using the primary data path, data is requested from the storage controller using one or more alternative data paths. Data is received from the storage controller on one of data paths and into a buffer. When the read instruction has completed and that the data is in the buffer, the application is notified. Each data path is associated with a buffer and the data is received into a buffer associated with the path. The application is informed which buffer holds the data and the application accesses the data from this buffer.

Abstract: A method implemented in a computer infrastructure having computer executable code having programming instructions tangibly embodied on a computer readable storage medium. The programming instructions are operable to determine whether a target disk of a map contains data unavailable to a downstream disk from an upstream disk in a FlashCopy cascade and detect whether the downstream disk has a copy of the data. Additionally, the programming instructions are operable to copy the data from the target disk to the downstream disk, if the target disk of the map contains data unavailable to the downstream disk from the upstream disk and the downstream disk does not have the copy of the data. Furthermore, the programming instructions are operable to refrain from copying the data from the target disk to the downstream disk, if the target disk of the map does not contain data unavailable to the downstream disk from the upstream disk or the downstream disk does have the copy of the data.

Abstract: A storage unit including redundant storage includes: a primary storage unit and a journal for managing execution of incomplete writing of data for at least two overlapping data segments, a reference table for tracking incomplete writes of data; and includes instructions for managing data by: monitoring writes of data to identify incomplete writes of data sharing at least one designated storage location of a primary media; reading the associated writes of data into the table; sequencing the associated writes of data; writing data in sequence order to each designated storage location of the primary media and providing the data in sequence order to secondary media with a sequence number; and at least one secondary storage unit including a duplicate record of data comprised within the primary media, each secondary storage unit equipped for ensuring recent data is not overwritten with prior data by controlling writes according to the sequence number.

Abstract: A storage unit adapted for use in a processing system, includes: a journal for managing execution of incomplete writing of data for at least two segments of data, wherein a designated storage location for the first write of data overlaps a least a portion of a designated storage location for the second write of data, wherein the journal includes a reference table for tracking incomplete writes of data; and, the journal includes machine executable instructions stored within machine readable media for performing the managing by: monitoring writes of data to identify incomplete writes of data sharing at least one designated storage location of a primary media; reading the associated writes of data into the reference table; sequencing the associated writes of data in the reference table; and writing the data in the reference table in sequence order to each designated storage location of the primary media and associated secondary media.

Abstract: Methods and systems for memory management. A method for memory management includes: maintaining a reference count for at least one first process associated with a portion of memory; maintaining a shared reference count for at least one second process associated with the portion of memory; and freeing the portion of memory when the shared reference count is decremented to zero.

Abstract: A method for minimizing latency of data transfer between the redundant storage controllers in a network-based storage controller system that utilizes adaptive data throttling. Each redundant storage controller monitors latency for round trip communications between the redundant controllers by calculating a time required to mirror a write to the other controller and receive a write acknowledge. An average latency for round trip communications between the redundant controllers during a fixed monitoring period is calculated, and at the end of each fixed monitoring period, the average latency is compared to a fixed latency to access the average time latency for mirroring writes is good, acceptable or unacceptable. If the average time latency is good, the one controller reduces or disables throttling for data transfers between the one controller and the server, and between the one controller and back-end storage, increasing a number of this type of data transfer that can be executed in parallel.

Abstract: A storage control apparatus cooperable with a plurality of controlled storage apparatus arranged in a cascade of point-in-time copy relationship. The apparatus includes: a rate control component operable to set a desired rate for making clean a first target one of the plurality of controlled storage apparatus; a comparator component responsive to a signal from the rate control component to request and receive metadata from the plurality of controlled storage apparatus and to identify discrepant metadata; and a copy initiator, responsive to the comparator component to identify discrepant metadata and to initiate a copy operation from a first target one of the plurality of controlled storage apparatus to a second target one of the controlled storage apparatus.

Abstract: An apparatus for controlling a configuration change in a storage system having a plurality of storage appliances with an I/O handler local to each storage appliance for transmitting and receiving I/O requests. A local volume mapper local to each storage appliance maps storage local to the storage appliance; a remote volume mapper local to each storage appliance maps storage remote from the or each storage appliance; and a spanning host interface layer responsive to detection of the configuration change receives and redirects I/O requests among the plurality of storage appliances.

Abstract: A method for migrating data between heterogeneous data storage devices within a storage area network is disclosed. A first virtualizer presents stored data as a first virtual disk, and then communicates a managed disk representation of the first virtual disk to a second virtualizer. After receiving the managed disk representation, the second virtualizer virtualizes the stored data from the managed disk representation as a second virtual disk. At such point, the stored data can be progressively migrated from the first virtualizer to the second virtualizer.

Abstract: A method for migrating data between heterogeneous data storage devices within a storage area network is disclosed. A first virtualizer presents stored data as a first virtual disk, and then communicates a managed disk representation of the first virtual disk to a second virtualizer. After receiving the managed disk representation, the second virtualizer virtualizes the stored data from the managed disk representation as a second virtual disk. At such point, the stored data can be progressively migrated from the first virtualizer to the second virtualizer.

Abstract: This invention relates to a method, system and computer program product for reading data from a storage controller in storage area network. A read data instruction is received from an application requesting data from the storage controller using a primary data path. If the data on the primary data path is not transferred in a defined time interval using the primary data path, data is requested from the storage controller using one or more alternative data paths. Data is received from the storage controller on one of data paths and into a buffer. When the read instruction has completed and that the data is in the buffer, the application is notified. Each data path is associated with a buffer and the data is received into a buffer associated with the path. The application is informed which buffer holds the data and the application accesses the data from this buffer.

Abstract: A host data processing system includes a data storage system having a cache memory and a back end storage. In response to a detection of an event failure during an input/output (I/O) request from the host data processing system to the data storage system, the data associated with the I/O request is forwarded to the back end storage data, and a copy of the data associated with the I/O request is sent to the cache memory. A determination is made as to whether or not there is an acknowledgement from the back end storage regarding the receipt of the data associated with the I/O request. If there is an acknowledgement from the back end storage regarding the receipt of the data associated with the I/O request, the data associated with the I/O request is flushed from the cache memory, and the received acknowledgement is routed to the host data processing system.