Emc IP Holding Company LLC

Emc Corporation

Symantec Operating Corporation

Diane Delgado

Philippe Armangau

William C Davenport

Christopher Alan Seibel

Ahsan Rashid

Alexei Karaban

Lawrence Yetto

Jean-Pierre Bono

Xiangping Chen

Feng Zhang

Rohit K Chawla

Sitaram D Pawar

John F Gillono

Kevin Rodgers

Hao Pan

Ron Passerini

Jeff Darcy

Tianming Zhang

Michael Rowan

Robert A Perry

Described are techniques for processing data. Hash values for the data portions of a logical device are determined. Each data portion has a corresponding one of the hash values. It is determined whether a first of the hash values associated with a first of the data portions is equal to a hash value of an implied data value. If the first hash value is equal to the hash value of the implied data value, first processing is performed including determining whether the first data portion has a current data value equal to the implied data value, and responsive to determining that the first data portion has a current data value equal to the implied data value, performing second processing including updating first metadata for the first data portion to denote that the first data portion has the implied data value. The first data portion is not associated with allocated storage.

Data deduplication techniques

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.

Managing copying of data in storage systems

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.

Allocating space in a file system from sequential and random cursors

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.

Data storage system with window allocation using window cache

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.

Data storage system with file system stream detection

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.

Coalescing transactional same-block writes for virtual block maps

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.

Managing global metadata caches in data storage systems

In a multiprocessor system that includes a plurality of processor modules, each one of which includes its own internal clock, one of the plurality of processor modules is designated as a master processor module having a master internal clock. Each other processor module is designated as a slave processor module having a slave processor module internal clock. Each slave processor module synchronizes its internal clock with the master internal clock.

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Carlisle, MA, United States of America

Diane Delgado