Abstract: A plurality of data units with associated timestamps is stored in a time based file system, wherein a timestamp corresponds to a time indicated by a system clock. A time indicated by the system clock is changed while the plurality of data units is being stored. A plurality of epochs is stored in a data structure, wherein an epoch is a period of time between a starting and an ending timestamp selected from the timestamps, and wherein successive epochs have overlapping time periods. The time based file system is reverted to an earlier point in time based on the plurality of epochs stored in the data structure.

Abstract: A plurality of tokens corresponding to a plurality of data units written to a rewritable file system is stored, wherein an ordering relationship is maintained among the plurality of tokens, wherein the ordering relationship is such that a first token corresponding to a first data unit is of a lesser numerical value in comparison to a second token corresponding to a second data unit, and wherein the first data unit is written at an earlier point in time in comparison to the second data unit. The rewritable file system is reverted to an indicated point in time based on the ordering relationship that is maintained among the stored plurality of tokens.

Abstract: An apparatus for collecting dump data collection receives an on demand data (ODD) dump request, pauses one or more scan loops, transfers dump data to an ODD dump buffer space, unpauses the scan loops, and offloads dump data from the ODD dump buffer space to the storage device. The apparatus may also prioritize dump data for transfer to the ODD dump buffer space, load balance dump data for transfer to the ODD dump buffer space, and schedule offloading of the dump data from the ODD dump buffer space to non-volatile storage.

Abstract: An apparatus, system, and method are disclosed for validating logical volume configuration. A determination module makes a determination of a type of a host operating system of a host computer requesting access to a logical volume. A characterization module characterizes the host type of the logical volume. A compatibility module determines if the logical volume is configured for the host operating system. A mitigation module mitigates the mis-configuration if the logical volume is not configured for the host operating system.

Abstract: Provided are a method, system, and article of manufacture for mirroring data between a first site and a second site. Updates to segments of storage at the first site are copied to corresponding segments of storage at the second site. Codes are generated from the segments at the second site and a valid flag is provided for at least one code indicating whether the code for the segment of data is valid. One code is generated from each segment of storage at the first site. An operation is initiated to copy segments from the second site to the first site. A determination is made for segments at the second site as to whether the valid flag for the code for the segment at the second site indicates that the code is valid in response to initiating the copy operation. The valid code for at least one segment in the second site is compared with the code for the corresponding segment at the first site to determine whether to copy the data from the segment at the second site to the first site as part of the copy operation.

Abstract: Provided are a method, system, and program to allocate tasks among a plurality of processes within a distributed processing environment. Each process secures a list of elements and performs a first operation on an element of the list to produce a result corresponding to one of the processes. If the result corresponds to the process processing the element, the process performs a second operation on the element. Each process then processes the next element on the list until all the elements of the list are processed. After the process processes all the elements on the list it further processes each element remaining on the list and performs the second operation on the elements remaining on the list. In one implementation, the distributed processing environment is a peer-to-peer virtual storage system and each process runs on a controller controlling a plurality of storage systems.

Abstract: A system and method, employing a data storage device, for providing communication between a plurality of processing units which are respectively unconnected to each other, with the processing units each separately coupled to the data storage device. A data storage device controller coupled to storage interfaces and to a buffer, recognizes “broadcast” commands and any message accompanying the “broadcast” commands, and recognizes “read message” commands, received from the processing units. The controller stores the message accompanying the “broadcast” command in the buffer, and forwards, at the storage interfaces, a “message ready” signal to at least one of the processing units. The processing units then send a “read message” command to the data storage device. The controller responds to a “read message” command at one of the storage interfaces, supplying the message stored in the buffer at the storage interface to the sending processing unit.

Abstract: A disk caching method for an intermediary controller is disclosed. Requests for data blocks are made and then disk caching is performed according to a most expedient cache method. The disk caching method may be performed by asynchronously requesting a data record from both a intermediary controller disk storage and from a intermediary controller cache and using a first received copy of the data record, the first received copy being a copy received first from the intermediary controller disk storage.

Abstract: Emulation of a small computer system interface (SCSI) library storage is provided in a virtual data storage subsystem having an automated tape library. This allows the ability to access or store a logical volume of data. Medium changer commands as used in SCSI and other open system interfaces are mapped to library function commands as commonly used in an enterprise server environment. This allows full transparent usage of virtual tape storage available in the enterprise server environment as open system storage.

Abstract: A multi-port adapter and method for scheduling jobs at the adapter input/output ports. A plurality of queues are provided, each associated with one of the input/output ports. A processor arranges the jobs in each of the queues in a normal queued order for selection by the associated port. Upon selecting a next job for one of the ports, the processor determines the number of queued jobs of each of the queues for each of the other ports; and determines whether the number of queued jobs of each queue for the other ports is less than a threshold. If the number of jobs is less than the threshold, the processor selects the next job for the one port from the jobs in the queue for the one port identified as one that may be conducted in out of queue order, e.g., having attached heuristic information; else, selects the next job for the one port from the jobs in the queue for the one port on the normal queued basis.

Abstract: Provided are a method, system, and program to allocate tasks among a plurality of processes within a distributed processing environment. Each process secures a list of elements and performs a first operation on an element of the list to produce a result corresponding to one of the processes. If the result corresponds to the process processing the element, the process performs a second operation on the element. Each process then processes the next element on the list until all the elements of the list are processed. After the process processes all the elements on the list it further processes each element remaining on the list and performs the second operation on the elements remaining on the list. In one implementation, the distributed processing environment is a peer-to-peer virtual storage system and each process runs on a controller controlling a plurality of storage systems.

Abstract: A system and method, employing a data storage device, for providing communication between a plurality of processing units which are respectively unconnected to each other, with the processing units each separately coupled to the data storage device. The data storage device is coupled to the processing units by means of peripheral or storage interfaces, each coupled to one of the processing units for receiving commands and signals sent from each of the processing units and for supplying signals to each of the processing units. A controller coupled to the storage interfaces and to a buffer, recognizes “broadcast” commands and any message accompanying the “broadcast” commands, and recognizes “read message” commands, received from the processing units.

Abstract: A data storage system stores data with a corresponding encapsulated metadata token in cache and/or base storage to protect against recalling stale data from base storage in the event of a cache failure and subsequent cache miss. A controller is coupled to a cache, base storage, and token database. After receiving a data object and associated write request, the controller assigns a version code to the data object. If the data object already exists, the controller advances the data object's version code. A token, including the version code along with other items of metadata, is encapsulated for storage. Then, the controller stores the data object and encapsulated token in cache and/or base storage and updates the token database to cross-reference the data object with its version code.

Abstract: A particularly efficient storage system makes redundant copies of data on tape by waiting until a rewind/unload command is received and then copying stored data objects en masse, thereby benefitting from any data compression used to store the objects along with the lower overhead for the copy operation. This copy operation is more efficient than the data objects' original storage, because there is less overhead in copying the data objects en masse; also, there is less data to copy if the data objects were stored with any data compression. Efficiency may be further increased by dividing the task of originally writing the data objects between paired tape drives, and then exchanging data objects between the tape drives upon issuance of the rewind/unload command.

Abstract: A system and method, employing a data storage device, for providing communication between a plurality of processing units which are respectively unconnected to each other, with the processing units each separately coupled to the data storage device. The data storage device is coupled to the processing units by means of peripheral or storage interfaces, each coupled to one of the processing units for receiving commands and signals sent from each of the processing units and for supplying signals to each of the processing units. A controller coupled to the storage interfaces and to a buffer, recognizes “broadcast” commands and any message accompanying the “broadcast” commands, and recognizes “read message” commands, received from the processing units.

Abstract: A data storage library system and a method for storing, and maintaining and tracking synchronism between, multiple copies of identifiable data volumes between hosts and a plurality of data storage libraries, and transparent to the hosts. The library controller of each library provides an updatable synchronization token directly associated with each data volume. A plurality of directors are provided, each separate from and coupled to the hosts and each separate from and coupled to each data storage library. Each director responds to ones of separate, partitioned access addresses addressed by the hosts. The responding director supplies each data volume supplied from a host to all of the data storage libraries, and updates each synchronization token directly associated with the supplied data volume. Thus, the directors store duplicate copies of the data volume in the data storage libraries without involvement by the host.

Abstract: A data storage library subsystem and a method for storing, and maintaining and tracking synchronism between, multiple copies of identifiable data volumes between hosts and a plurality of data storage libraries, and transparent to the hosts. The library controller of each library provides an updatable synchronization token directly associated with each data volume. A plurality of directors are provided, each separate from and coupled to the hosts and each separate from and coupled to each data storage library. Each director responds to ones of separate, partitioned access addresses addressed by the hosts. The responding director supplies each data volume supplied from a host to all of the data storage libraries, and updates each synchronization token directly associated with the supplied data volume. Thus, the directors store duplicate copies of the data volume in the data storage libraries without involvement by the host.

Abstract: A disk caching method for an intermediary controller is disclosed. Requests for data blocks are made and then disk caching is performed according to a most expedient cache method. The disk caching method may be performed by asynchronously requesting a data record from both a intermediary controller disk storage and from a intermediary controller cache and using a first received copy of the data record, the first received copy being a copy received first from the intermediary controller disk storage.

Abstract: Identifying most recent redundant copies of identifiable data volumes stored in a plurality of data storage libraries which are coupled to a plurality of directors. To update a data volume, an initiating director attempts to set a current token “inconsistent” flag to potentially down level copies of the data volume on each lagging library. Upon failing to receive notification of any successful setting of the current token “inconsistent” flag from any of the lagging libraries, the director forwards the request to the other directors, which attempt to set the current token “inconsistent” flag for the volume at any lagging library from which no notification has been received. Upon all of the other directors responding to the initiating director, and upon the other directors indicating failure to set the “inconsistent” flag at the lagging library, all the directors list the volume and a new token as an entry in a “hot token” list.

Abstract: A file translation system and a physical information and extensions file for an intermediary controller is disclosed. The file translation system that allow a host computer to directly access data from a different host type without moving the actual data. The physical information and extension file provides information concerning the location of data and the file system the host is viewing. The intermediary controller is disposed between a legacy disk controller for an originating host of a first type and an open system host. The intermediary controller emulates a virtual storage device using a virtual device file system, wherein the virtual device file system mapping data stored in a storage device by the originating host to objects in a root directory in the virtual device file system.