Abstract: Techniques are disclosed in which a computer system implements schema changes for existing database objects by maintaining a logical name and a current physical name corresponding to an existing database object, where the logical name points to the current physical name. The system receives a schema change request specifying the logical name and format changes for the existing object. The system performs a schema change operation in response to the request, including: creating a new database object having a new physical name, copying and transforming data from the existing object to the new object according to the format changes, mirroring new writes directed to the logical name to both the existing and new objects, and causing the logical name to point to the new physical name instead of the current physical name after completing the copying. The system responds to subsequent queries, specifying the logical name, from the new object.

Abstract: A database system is disclosed. The database system may receive a plurality of records representing changes made to a plurality of datasets, and the plurality of records may include a plurality of data change instances associated with a plurality of data schema types. The plurality of data change instances may correspond to a plurality of respective keys. The database system may compute an average size of data for each data schema type of the plurality of data schema types. The database system may modify the plurality of respective keys through a salting process, which may include assigning non-overlapping numerical ranges to subsets of the plurality of respective keys. The database system may sort, using the non-overlapping numerical ranges, the plurality of data change instances into a plurality of partitions of a target file size. The database system may write files of the target file size to a data store.

Abstract: Techniques are disclosed in which a computer system implements schema changes for existing database objects by maintaining a logical name and a current physical name corresponding to an existing database object, where the logical name points to the current physical name. The system receives a schema change request specifying the logical name and format changes for the existing object. The system performs a schema change operation in response to the request, including: creating a new database object having a new physical name, copying and transforming data from the existing object to the new object according to the format changes, mirroring new writes directed to the logical name to both the existing and new objects, and causing the logical name to point to the new physical name instead of the current physical name after completing the copying. The system responds to subsequent queries, specifying the logical name, from the new object.

Abstract: Techniques are disclosed in which a computer system implements schema changes for existing database objects by maintaining a logical name and a current physical name corresponding to an existing database object, where the logical name points to the current physical name. The system receives a schema change request specifying the logical name and format changes for the existing object. The system performs a schema change operation in response to the request, including: creating a new database object having a new physical name, copying and transforming data from the existing object to the new object according to the format changes, mirroring new writes directed to the logical name to both the existing and new objects, and causing the logical name to point to the new physical name instead of the current physical name after completing the copying. The system responds to subsequent queries, specifying the logical name, from the new object.

Abstract: A system and method for improving deduplication techniques in a data storage system. In one embodiment, a data storage system is configured to divide first data into a first plurality of segments, to generate a first plurality of fingerprints that are each to be associated with a segment, to identify second data that is to be updated by the first data and a second plurality of fingerprints associated with the second data, to load the second data and the second plurality of fingerprints from persistent storage of the data storage system into working memory, to determine, in the working memory, that a first segment of the first plurality of segments updates the second data by comparing a first fingerprint associated with the first segment to the second plurality of fingerprints, and to overwrite a second segment of the second data with the first segment in response to the determination.

Abstract: A method, article of manufacture, and apparatus for restoring LUs from a backup is discussed. In an embodiment, a primary storage system may continue to process IOs while the LU is being restored.

Abstract: In one aspect, a method includes replicating a first volume to a consistency group (CG) file on a backup device. The method also includes replicating a second volume to the CG file concurrently with the replicating of the first volume, the first and second volumes being in a consistency group.

Abstract: A system and method for generating synthetic data to simulate backing up data between a primary storage system and a protection storage system is presented. In one embodiment, a first track in a set of tracks is selected at random. Having selected a first track, at least a first block in the first track is modified. Subsequently, it is determined, based on a track run probability, whether to modify a second track that is consecutive to the first track or a third track that is selected randomly. Depending on the determination, at least one block is modified at either the second or third track. Other embodiments are also described herein.

Abstract: A method for quickly identifying data residing on a volume in a multivolume file system. The method includes generating a file location map, the file location map containing a list of the locations of files that occupy space on each of a plurality of volumes of the file system. The file system comprises least a first volume and a second volume. The file location map is updated in accordance with changes in a file change log for the file system. Data residing on the first volume of the file system is identified by scanning the file location map.

Abstract: A computer-implemented method and apparatus manages block mapping. The block mapping maps physical blocks in a block storage device to virtual blocks of a virtual address space. The method involves assigning a generation number from a net of generation numbers to each block mapping entry, where the block mapping entry correlates a physical block with a virtual block. A maximum generation number of the set of generation numbers is increased and a first block mapping entry is marked dirty in response to an update of a correlated first virtual block. A generation number of the first block mapping entry is set to the maximum generation number. Finally, a generation number of a second block mapping entry having a lowest generation number is set to a generation number of the first block mapping entry.

Abstract: A system and method for writing data a series of partial stripe writes to a redundant array of independent disks (RAID) with parity system. In one embodiment, the RAID with parity system is implemented as a log-structured storage system. In the RAID with parity system, each of the partial stripe writes can be issued before the active stripe is fully written. To buffer each partial stripe write, some data from each partial stripe write can be written to a scratch stripe before being written to the active stripe so that only writes of a predetermined size are issued to the active stripe. Other embodiments are also described herein.

Abstract: A partial replication step shot method. The method includes receiving a first snapshot at a first time from a replication source and receiving a set of data objects from the replication source that have been modified during a time period between the first time and a subsequent second time. A second snapshot is generated at the second time on the replication source by using the set of data objects. An application is mounted onto the second snapshot prior to the set of data objects being received to completion.

Abstract: A method for identifying data for relocation in a multivolume file system. The method includes generating a file location map, the file location map containing a list of the locations of files that occupy space on each of a plurality of volumes of the file system, wherein The file system comprising least a first volume and a second volume. The method further includes updating the file location map in accordance with changes in a file change log for the file system, and identifying data residing on the first volume of the file system by scanning the file location map. Using the identified data, a ratio of per-file activity during a first time period relative to overall file system activity over a second time period is calculated to derive a file activity ratio for each of the files of the identified data. Files are then selected for relocation based on the file activity ratio.

Abstract: Various systems and methods are disclosed to share a single copy of a storage object among clones. For example, one method involves creating a first and second clone. The first and second clones share a single copy of a storage object. The first clone is assigned an identifier based on the value of a variable. After creating the first clone the variable is incremented. The second clone is assigned the value of the incremented variable as an identifier.

Abstract: A system and method for logging for asynchronously replicating volume groups. A write request to write data to a location in a volume may be received. Metadata associated with the write request may be stored. It may be determined if the write request possibly overlaps with one or more earlier write requests to the volume that have not yet been replicated to a secondary storage. The data may be stored in a replication log only if the write request possibly overlaps with one or more earlier write requests to the volume. The data may not be stored in the replication log if the write request does not overlap with one or more earlier write requests to the volume. The data may be written to the location in the volume. Changes to the volume may periodically be replicated to the secondary storage using the replication log.

Abstract: System and method for tracking changes to a volume. A write request to write data to a first location in the volume may be received. It may be determined if the first location is overlapping with or adjacent to one or more locations of earlier write requests to the volume. First location information may be stored in a data structure in response to determining that the first location is overlapping with or adjacent to one or more second locations of earlier write requests to the volume. The first location information may identify the first location and the one or more second locations. Second location information may be removed from the data structure, where the second location information identifies the one or more second locations of earlier write requests to the volume. The data may be written to the first location in the volume in response to the write request.

Abstract: A partial replication step shot method. The method includes receiving a first snapshot at a first time from a replication source and receiving a set of data objects from the replication source that have been modified during a time period between the first time and a subsequent second time. A second snapshot is generated at the second time on the replication source by using the set of data objects. An application is mounted onto the second snapshot prior to the set of data objects being received to completion.

Abstract: A method for quickly identifying data residing on a volume in a multivolume file system. The method includes generating a file location map, the file location map containing a list of the locations of files that occupy space on each of a plurality of volumes of the file system. The file system comprises least a first volume and a second volume. The file location map is updated in accordance with changes in a file change log for the file system. Data residing on the first volume of the file system is identified by scanning the file location map.

Abstract: A method for identifying data for relocation in a multivolume file system. The method includes generating a file location map, the file location map containing a list of the locations of files that occupy space on each of a plurality of volumes of the file system, wherein The file system comprising least a first volume and a second volume. The method further includes updating the file location map in accordance with changes in a file change log for the file system, and identifying data residing on the first volume of the file system by scanning the file location map. Using the identified data, a ratio of per-file activity during a first time period relative to overall file system activity over a second time period is calculated to derive a file activity ratio for each of the files of the identified data. Files are then selected for relocation based on the file activity ratio.

Abstract: System and method for tracking changes to a volume. A write request to write data to a first location in the volume may be received. It may be determined if the first location is overlapping with or adjacent to one or more locations of earlier write requests to the volume. First location information may be stored in a data structure in response to determining that the first location is overlapping with or adjacent to one or more second locations of earlier write requests to the volume. The first location information may identify the first location and the one or more second locations. Second location information may be removed from the data structure, where the second location information identifies the one or more second locations of earlier write requests to the volume. The data may be written to the first location in the volume in response to the write request.