Abstract: A method for managing a data storage system includes maintaining a record on a secondary storage subsystem, which is predictive of locations to which data are to be written on a primary storage subsystem by a host processor. Upon receiving at the primary storage subsystem, from a host processor, the data to be written to a specified location, if the specified location is not included in the record, the primary storage subsystem sends to the secondary storage subsystem so as to cause the secondary storage subsystem to update the record. The primary storage subsystem signals the host processor that the data have been stored in the data storage system responsively to receiving the data and to receiving an acknowledgment from the secondary storage subsystem indicating that the record has been updated.

Abstract: An apparatus for optimizing a transaction comprising an initial sequence of computer operations, the apparatus includes a processing unit which identifies one or more idempotent operations comprised within the initial sequence, and which reorders the initial sequence to form a reordered sequence comprising a first sub-sequence of the computer operations followed by a second sub-sequence of the computer operations, the second sub-sequence comprising only the one or more idempotent operations.

Abstract: An apparatus, system, and method are disclosed for a read-before-write storage controller instruction. A sequencer receives an atomic read-before-write instruction comprising new data, a target address for the new data, and an undo log address. An I/O unit reads old data from the target address, writes the old data and the target address to the undo log address, and writes the new data to the target address as directed by the sequencer.

Abstract: Generating a consistent point in time copy of data in a source volume and a target volume is achieved responsively to a first data modification request by writing a first altered version of the data onto a single source volume, asynchronously transferring the first altered version from the first storage site to a target volume located at a remote second storage site, while avoiding copying the first altered version onto other volumes at the first storage site. While asynchronously transferring the first altered version de-queuing a second modification request, and responsively to the second modification request synchronously transferring the first altered version from the first storage site to the target volume. Then a second altered version of the data is written to the single source volume and a copy transferred to the target volume in like manner.

Abstract: A method that can simplify a recovery of a system. The method includes storing multiple types of information, and includes: a first stage of storing information representative of a content of a persistent memory entity at a certain point in time; and a second stage of storing information representative of a state of a virtual machine at the certain point in time; and recovering a system that associates between the first stage of storing information and the second stage of storing information.

Abstract: Provided are a method, system, and article of manufacture wherein a command is received for writing data to a first storage location. A determination is made that previously written data is stored in the first storage location. The previously written data is copied to a second storage location, in response to determining that the previously written data is stored in the first storage location. The data is written to the first storage location, in response to copying the previously written data to the second storage location.

Abstract: An apparatus for optimizing a transaction comprising an initial sequence of computer operations, the apparatus includes a processing unit which identifies one or more idempotent operations comprised within the initial sequence, and which reorders the initial sequence to form a reordered sequence comprising a first sub-sequence of the computer operations followed by a second sub-sequence of the computer operations, the second sub-sequence comprising only the one or more idempotent operations.

Abstract: A method for optimizing a transaction consisting of an initial sequence of computer operations, the method including identifying one or more idempotent operations in the initial sequence. The method further includes reordering the initial sequence to form a reordered sequence consisting of a first sub-sequence of the computer operations followed by a second sub-sequence of the computer operations. The second sub-sequence has only the one or more idempotent operations.

Abstract: A method for generating a consistent point in time copy of data, the method includes: selecting at least one selected data block to be copied from a source volume to a target volume in response to a request to generate a consistent point in time copy of multiple data blocks; waiting until the source volume is ready to send the at least one selected data block to a remote volume while queuing at least one data block modify request; de-queuing the at least one queued modify requests while copying the at least one selected data block from the source volume to the target volume; wherein the copying includes utilizing a first copying mechanism to copy a first selected data block if a request to modify the first selected block is de-queued before the first selected data block is copied to the target volume; else, the copying includes using a second copying mechanism that is slower than the first copying mechanism.

Abstract: Generating a consistent point in time copy of data in a source volume and a target volume is achieved responsively to a first data modification request by writing a first altered version of the data onto a single source volume, asynchronously transferring the first altered version from the first storage site to a target volume located at a remote second storage site, while avoiding copying the first altered version onto other volumes at the first storage site. While asynchronously transferring the first altered version de-queuing a second modification request, and responsively to the second modification request synchronously transferring the first altered version from the first storage site to the target volume. Then a second altered version of the data is written to the single source volume and a copy transferred to the target volume in like manner.

Abstract: An apparatus, system, and method are disclosed for a read-before-write storage controller instruction. A sequencer receives an atomic read-before-write instruction comprising new data, a target address for the new data, and an undo log address. An I/O unit reads old data from the target address, writes the old data and the target address to the undo log address, and writes the new data to the target address as directed by the sequencer.

Abstract: A system and method for a desk checker includes a partial state representation, a simulator controller to access the partial state representation and to continue a simulation without state information, and a desk checking component controlled by the simulator controller. The desk checking component includes any of a user interface, a static analysis engine, a partial execution component, and an analyzer. The system and method for desk checking includes simulating code execution on a computing device with partial state information and requesting user input to supplement the partial state information.

Abstract: A method for generating a consistent point in time copy of data, the method includes: selecting at least one selected data block to be copied from a source volume to a target volume in response to a request to generate a consistent point in time copy of multiple data blocks; waiting until the source volume is ready to send the at least one selected data block to a remote volume while queuing at least one data block modify request; de-queuing the at least one queued modify requests while copying the at least one selected data block from the source volume to the target volume; wherein the copying includes utilizing a first copying mechanism to copy a first selected data block if a request to modify the first selected block is de-queued before the first selected data block is copied to the target volume; else, the copying includes using a second copying mechanism that is slower than the first copying mechanism.

Abstract: The present invention provides a method, an apparatus and a computer program product for transferring a digital object from a source to a destination. The method includes splitting the digital object into a plurality of parts forming a first set of parts and a set of remaining parts. The method creates a credential record defining a relationship between the plurality of parts. The credential record includes retrieval information for the set of remaining parts. The method further includes transferring a first set of the parts along with the credential record to the destination using at least one push path. The method further includes fetching the set of remaining parts at the destination using the credential record to connect the destination to the source via at least one pull path. Further, the method includes recreating the digital object at the destination using the first set of parts, the credential record and a set of remaining parts.

Abstract: A method for storing multiple types of information, the method includes: storing information representative of a content of a persistent memory entity at a certain point in time; and storing information representative of a state of a virtual machine at the certain point in time. A computer program product including a computer usable medium including a computer readable program, wherein the computer readable program when executed on a computer causes the computer to: store information representative of a content of a persistent memory entity at a certain point in time; and store information representative of a state of a virtual machine at the certain point in time.

Abstract: Provided are a method, system, and article of manufacture wherein a command is received for writing data to a first storage location. A determination is made that previously written data is stored in the first storage location. The previously written data is copied to a second storage location, in response to determining that the previously written data is stored in the first storage location. The data is written to the first storage location, in response to copying the previously written data to the second storage location.

Abstract: A method for managing a data storage system includes copying data stored on a first storage subsystem to a second storage subsystem in an asynchronous mirroring process. A record is maintained on the second storage subsystem, indicative of locations at which the data have been updated on the first storage subsystem and have not yet been copied to the second storage subsystem. Upon receiving at the second storage subsystem, from a host processor, a request to access the data stored at a specified location on the data storage system, if the specified location is included in the record, the second storage subsystem initiates a synchronous transfer of the data at the specified location from the first storage subsystem.

Abstract: A system and method for a desk checker includes a partial state representation, a simulator controller to access the partial state representation and to continue a simulation without state information, and a desk checking component controlled by the simulator controller. The desk checking component includes any of a user interface, a static analysis engine, a partial execution component, and an analyzer. The system and method for desk checking includes simulating code execution on a computing device with partial state information and requesting user input to supplement the partial state information.

Abstract: Provided are a method, system, and program for managing a relationship between one target volume and one source volume. Information is maintained in memory on an existing relationship between at least one source volume and at least one target volume, comprising: (i) at least one element, wherein each element represents a range of sequential data units in the volume; (ii) at least one relationship entry, wherein each relationship entry represents one relationship; and (iii) at least one element pointer associating one element with one relationship entry, wherein the data units represented by the element are part of the relationship represented by the relationship entry that the pointer associates with the element. A new relationship between at least one target volume and at least one source volume is added.

Abstract: Provided are a method, system, and program for managing a relationship between one target volume and one source volume. For each of the source volume and target volume, the memory includes: (i) at least one element, wherein each element represents a range of sequential data units in the volume; (ii) at least one relationship entry, wherein each relationship entry represents one relationship; (iii) at least one element pointer associating one element with one relationship entry, wherein the data units represented by the element are part of the relationship represented by the relationship entry that the pointer associates with the element; and (iv) one relationship pointer for each relationship entry associating the relationship entry with volume metadata, wherein the volume metadata provides information on the relationship represented by the relationship entry.