Abstract: A method is used in managing copying of data in storage systems. A request is received to copy a portion of a source logical object to a target logical object. The source and target logical objects are subject to a deduplicating technique. The portion of the source logical object is copied to the target logical object by updating metadata of the target logical object. The target logical object shares the portion of the source logical object.

Abstract: A technique for storage allocation provides a first cursor and a second cursor from which to allocate blocks within a physical address space of a file system. The file system uses the first cursor for allocating blocks for writes directed to sequential logical addresses and uses the second cursor for writes directed to random (non-sequential) logical addresses.

Abstract: A method of operating a data storage system includes writing the file system data as sequential data and non-sequential data to a storage volume, the sequential data being stored in windows each having a predetermined number of consecutive data blocks and being allocated dynamically as the sequential data is written. The method includes maintaining and using a window cache to identify existing windows for storing respective newly written sequential file system data in sequence with respective earlier-written file system data for which the existing windows were previously allocated, the window cache including a set of entries indexed by an identifier of (1) a file of the file system and (2) a window-size region of the file to which sequential data is being written, the entries including respective physical window addresses identifying respective ones of the existing windows and being obtained by lookup operations using respective values of the identifier.

Abstract: A data storage system includes an internal file system writing file system data to an underlying storage volume. File system data is written as sequential data and non-sequential data, the sequential data stored in dynamically allocated windows having a predetermined number of data blocks. Operation includes stream detection that detects and identifies sequential data by (1) applying nearness detection to identify newly written data blocks as sequential data blocks located within a predetermined address range of previously data blocks, (2) for groups of written data blocks occupying respective single files, maintaining counts of the data blocks identified by the nearness detection as sequential data blocks, and (3) as additional data blocks are newly written to the groups and not identified by the nearness detection as sequential data blocks, performing overrides identifying the additional data blocks as sequential data blocks based on the counts exceeding a predetermined threshold.

Abstract: A technique for preserving metadata changes in a transaction log involves coalescing metadata changes based on the block of storage in which the metadata to be changed resides. Metadata change information that accompanies a file system command is stored in nodes of a searchable data structure, wherein each node accumulates metadata changes for a respective block of storage. Once all metadata changes are specified in the searchable data structure, or after some threshold number of metadata changes have been stored, the storage processor composes a transaction for each node summarizing the metadata changes and writes the transaction to the transaction log.

Abstract: A method is used in managing global metadata caches in data storage systems. Space is allocated in a memory of a data storage system to a global metadata cache which is configured to store metadata objects for a plurality of different file systems responsive to file system access requests from the plurality of different file systems. A metadata object associated with a file of a file system of the plurality of different file systems is stored in the global metadata cache. The metadata object is accessed by a plurality of different versions of the file.