Abstract: An apparatus for improved version updates in data deduplication includes a baseline module that stores a baseline referrer link in a first cohort of baseline referrer links pointing to a first location in storage where a baseline version data block is stored. The apparatus includes a signpost module that stores to metadata a signpost that points to an updated referrer link in a second cohort of updated referrer links that points to a second location in the deduplicating storage device where an updated version data block is stored in response to the updated version data block being generated. The apparatus includes a cohort update module that replaces the baseline referrer link with the updated referrer link in response to determining that an additional updated version data block matches the updated version data block pointed to by the signpost. A method and a system implement functions of the apparatus.

Abstract: Managing storage volumes in a point-in-time copy cascade. The cascade includes a first source volume, a first target volume and a second target volume. The method detects a corruption of the first source volume and, if a first restoration of the first source volume from the first target volume is in progress, creates a third target volume from the second target volume and directs I/O operations for the first source volume to the third target volume. The first source volume is then restored from the third target volume.

Abstract: A computer-implemented method of storing data on a storage device can receive an I/O request to read data from or write data to a data storage device. The data can be stored in special sectors as allocated sectors and regular sectors as a log-structured array (LSA). If the I/O request is to read data from the storage device, a determination can be made as to whether the data to be read is stored as a special sector, which can be read from the LSA, or as a regular sector, which can be can be read from the allocated sectors. If the I/O request is to write data to the storage device, a determination can be made as to whether the data to be written is stored as a special sector, to the LSA or as a regular sector, to the allocated sectors.

Abstract: A computer-implemented method of storing data on a storage device can receive an I/O request to read data from or write data to a data storage device. The data can be stored in special sectors as allocated sectors and regular sectors as a log-structured array (LSA). If the I/O request is to read data from the storage device, a determination can be made as to whether the data to be read is stored as a special sector, which can be read from the LSA, or as a regular sector, which can be can be read from the allocated sectors. If the I/O request is to write data to the storage device, a determination can be made as to whether the data to be written is stored as a special sector, to the LSA or as a regular sector, to the allocated sectors.

Abstract: An apparatus for improved version updates in data deduplication includes a baseline module that stores a baseline referrer link in a first cohort of baseline referrer links pointing to a first location in storage where a baseline version data block is stored. The apparatus includes a signpost module that stores to metadata a signpost that points to an updated referrer link in a second cohort of updated referrer links that points to a second location in the deduplicating storage device where an updated version data block is stored in response to the updated version data block being generated. The apparatus includes a cohort update module that replaces the baseline referrer link with the updated referrer link in response to determining that an additional updated version data block matches the updated version data block pointed to by the signpost. A method and a system implement functions of the apparatus.

Abstract: A method, computer system, and a computer program product for point-in-time copy with target write optimization in a cascading copy-on-write process is provided. The present invention may include receiving a request to perform a point-in-time copy operation to create a point-in-time copy from a source volume to a target volume. The present invention may include creating an intermediate volume, an intermediate map, and a map for the target volume. The present invention may include making the intermediate volume dependent on the source volume in a dependency chain based on the intermediate map. The present invention may include making the target volume dependent on the intermediate. The present invention may include allocating a new stream identifier to the target volume. The present invention may also include updating upstream volumes to inherit the new stream identifier as well as maintaining any existing stream identifiers.

Abstract: Managing storage volumes in a point-in-time copy cascade. The cascade includes a first source volume, a first target volume and a second target volume. The method detects a corruption of the first source volume and, if a first restoration of the first source volume from the first target volume is in progress, creates a third target volume from the second target volume and directs I/O operations for the first source volume to the third target volume. The first source volume is then restored from the third target volume.

Abstract: A method, computer system, and a computer program product for point-in-time copy with target write optimization in a cascading copy-on-write process is provided. The present invention may include receiving a request to perform a point-in-time copy operation to create a point-in-time copy from a source volume to a target volume. The present invention may include creating an intermediate volume, an intermediate map, and a map for the target volume. The present invention may include making the intermediate volume dependent on the source volume in a dependency chain based on the intermediate map. The present invention may include making the target volume dependent on the intermediate. The present invention may include allocating a new stream identifier to the target volume. The present invention may also include updating upstream volumes to inherit the new stream identifier as well as maintaining any existing stream identifiers.

Abstract: Managing storage volumes in a point-in-time copy cascade. The cascade includes a first source volume, a first target volume and a second target volume. The method detects a corruption of the first source volume and, if a first restoration of the first source volume from the first target volume is in progress, creates a third target volume from the second target volume and directs I/O operations for the first source volume to the third target volume. The first source volume is then restored from the third target volume.

Abstract: A first data storage device receives a first write request from a host device to update a first subset of the data regions and sends the first write request to a second data storage device. Prior to receiving a notification from the second device that it has been updated in accordance with the first write request, the first device receives a second write request from the second device to update a second subset of the data regions and one of the two devices is selected. If the first device is selected, the first device updates only its data regions that are in the second subset but not in the first subset according to the second write request. In the case that the second device is selected, the first device updates its data regions that are in the second subset according to the second write request.

Abstract: A system, method, and computer program product for managing storage volumes in a point-in-time copy cascade. A processor swaps a host portion of a source volume with a host portion of a snapshot point-in-time copy volume. Responsive to an I/O request to overwrite a first data value in a grain of the source volume with a second data value, a processor writes the second data value in a corresponding grain of the snapshot point-in-time copy volume. Responsive to a corresponding grain of a clone point-in-time copy volume not comprising the first data value, a processor copies the first data value to the corresponding grain of the clone point-in-time copy volume.

Abstract: A method for storage volumes in a cascade of storage volumes including starting a first data map relating a first storage volume to a second storage volume while a second data map relating the first storage volume and a third storage volume is active. Starting the first data map uses a zone map that relates the first storage volume to a zone within the cascade of storage volumes.

Abstract: A system, method, and computer program product for managing storage volumes. A processor creates a first point-in-time copy cascade, where the first point-in-time copy cascade comprises a source volume, a first snapshot point-in-time copy volume, and a second snapshot point-in-time copy volume; the first volume is a snapshot copy of the source volume and the second volume is a snapshot copy of the first volume. A processor creates a third snapshot point-in-time copy volume from the first volume. A processor maps the third volume to create a second cascade, wherein the second cascade comprises the source volume, the first volume, and the third volume but not the second volume. A processor directs an I/O operation for the first copy volume to the third volume.

Abstract: A system, method, and computer program product for managing storage volumes in a point-in-time copy cascade. A processor swaps a host portion of a source volume with a host portion of a snapshot point-in-time copy volume. Responsive to an I/O request to overwrite a first data value in a grain of the source volume with a second data value, a processor writes the second data value in a corresponding grain of the snapshot point-in-time copy volume. Responsive to a corresponding grain of a clone point-in-time copy volume not comprising the first data value, a processor copies the first data value to the corresponding grain of the clone point-in-time copy volume.

Abstract: A system, method, and computer program product for managing storage volumes in a point-in-time copy cascade. A processor swaps a host portion of a source volume with a host portion of a snapshot point-in-time copy volume. Responsive to an I/O request to overwrite a first data value in a grain of the source volume with a second data value, a processor writes the second data value in a corresponding grain of the snapshot point-in-time copy volume. Responsive to a corresponding grain of a clone point-in-time copy volume not comprising the first data value, a processor copies the first data value to the corresponding grain of the clone point-in-time copy volume.

Abstract: A system, method, and computer program product for managing storage volumes. A processor creates a first point-in-time copy cascade, where the first point-in-time copy cascade comprises a source volume, a first snapshot point-in-time copy volume, and a second snapshot point-in-time copy volume; the first volume is a snapshot copy of the source volume and the second volume is a snapshot copy of the first volume. A processor creates a third snapshot point-in-time copy volume from the first volume. A processor maps the third volume to create a second cascade, wherein the second cascade comprises the source volume, the first volume, and the third volume but not the second volume. A processor directs an I/O operation for the first copy volume to the third volume.

Abstract: A method for storage volumes in a cascade of storage volumes including starting a first data map relating a first storage volume to a second storage volume while a second data map relating the first storage volume and a third storage volume is active. Starting the first data map uses a zone map that relates the first storage volume to a zone within the cascade of storage volumes.

Abstract: A system, method, and computer program product for managing storage volumes. A processor creates a first point-in-time copy cascade, where the first point-in-time copy cascade comprises a source volume, a first snapshot point-in-time copy volume, and a second snapshot point-in-time copy volume; the first volume is a snapshot copy of the source volume and the second volume is a snapshot copy of the first volume; and the source volume, the first volume, and the second volume include a host portion. A processor creates a third snapshot point-in-time copy volume from the first volume. A processor maps the third volume to create a second cascade, wherein the second cascade comprises the source volume, the first volume, and the third volume but not the second volume. A processor directs an I/O operation for the first copy volume to the third volume.

Abstract: A method for storage volumes in a cascade of storage volumes including starting a first data map relating a first storage volume to a second storage volume while a second data map relating the first storage volume and a third storage volume is active. Starting the first data map uses a zone map that relates the first storage volume to a zone within the cascade of storage volumes.

Abstract: Managing storage volumes in a point-in-time copy cascade. The cascade includes a first source volume, a first target volume and a second target volume. The method detects a corruption of the first source volume and, if a first restoration of the first source volume from the first target volume is in progress, creates a third target volume from the second target volume and directs I/O operations for the first source volume to the third target volume. The first source volume is then restored from the third target volume.