Emc Corporation

Emc IP Holding Company LLC

Novell, Inc.

Michael Scheer

Morgan A Clark

Jean-Pierre Bono

William C Davenport

Ahsan Rashid

Pranit Sethi

Philippe Armangau

Sairam Veeraswamy

Alexander S Mathews

Marc DeSouter

Miles Aram De Forest

Walter Forrester

Feng Zhang

Rohit K Chawla

Srinivasa Rao Vempati

Hongliang Tang

Michael D Schouten

Maher Kachmar

Jonathon E Shopiro

A technique for managing block allocation in data storage systems involve providing multiple ranges of contiguous logical addresses (logical windows) in a logical address space of a file and allocating contiguous ranges of physical addresses (physical windows) in a file system to respective logical windows in response to requests to write data to logical addresses within the logical windows. When allocating blocks from one or more streams, each logical window to which writes are directed is mapped to a respective physical window, and each logical address in the logical window is mapped to a physical address in the physical window.

Window-based resource allocation in data storage systems

An improved technique involves identifying the location of backed free blocks, i.e., blocks within an upper deck file system that have been provisioned from storage devices of a data storage system to a lower deck file system, allocated from the lower deck file system to the upper deck file system, and later freed from the upper deck file system. A storage processor accesses a set of data structures that identifies backed free blocks as opposed to free blocks that have not been written into and thus do not correspond to any allocated blocks in storage. Once the storage processor identifies the backed free blocks, the storage processor frees each block in the lower deck file system from which the respective backed free block was allocated. The storage processor then updates the set of data structures to indicate that the respective backed free block is now simply a free block.

Efficient scavenging of data and metadata file system blocks

A technique for managing storage tiering in a data storage apparatus operates at a fine level of granularity in response to write requests as blocks are allocated for writing. As write requests arrive or are otherwise processed by the data storage apparatus, the data storage apparatus identifies a quality of service to be provided for satisfying each write request and allocates a set of blocks from storage devices of storage tiers that provide the identified quality of service. The data storage apparatus may then store the information specified in the write request in the newly allocated blocks.

File system inline fine grained tiering

A technique for managing a file system includes dividing the addressable space of a file system into multiple subspaces: a data subspace for user data; an inode subspace for inodes describing the user data; and an MDB (metadata block) subspace for indirect blocks and/or directory structures pertaining to the user data. In response to storage requests to write user files to the file system, the file system stores user data of the files in the data subspace, stores inodes pertaining to the user files in the inode subspace, and stores indirect blocks and/or directories in the MDB subspace.

Segregating data and metadata in a file system

A method, computer program product, and computing system for grouping storage blocks within a file system into a plurality of storage pools including a free-backed storage pool, a free-unbacked storage pool, and an allocated-backed storage pool. The free-backed storage pool identifies unused storage blocks within the file system that are already associated with physical storage space within a backend storage system. The free-unbacked storage pool identifies unused storage blocks within the file system that are not yet associated with physical storage space within the backend storage system. The allocated-backed storage pool identifies used storage blocks within the file system that are already associated with physical storage space within the backend storage system. A request is received for one or more unused storage blocks within the file system. The request is fulfilled by selecting one or more unused storage blocks identified within the storage pools while prioritizing the selection of unused storage blocks identified within the free-backed storage pool.

System and method for thin provisioning

An improved technique generates formatted file system metadata in increments only when metadata for those increments are specifically requested. A location on a storage volume designated for storing file system metadata is read and tested to determine whether it stores a predetermined pattern indicating an unformatted state. If the pattern is found, metadata for the designated location are generated and returned. Otherwise, metadata are returned as initially read from the storage volume.

Just-in time formatting of file system metadata

For enabling a fast reverse lookup of parent directories storing records of hard links to a specified regular file, a file system manager maintains a hard link database (HLDB) storing information for addressing hard links to the regular files having multiple hard links. The HLDB contains a corresponding HLDB file for each regular file having multiple hard links. In a preferred implementation, the inode of each regular file stores the addressing information for one hard link to the regular file, a corresponding HLDB file stores the addressing information for other hard links to the regular file, each HLDB file is a directory accessed by invoking file system manager directory access routines, and the HLDB has a directory tree providing a multi-level hash index for searching the HLDB given the inode number of a regular file.

Inode to pathname support with a hard link database

In a file server, a file system is built upon a volume of data storage. The file system includes multiple cylinder groups. Each cylinder group includes file system blocks. The file system blocks include allocated blocks and free blocks. The volume includes slices of storage, and each slice stores at least one of the cylinder groups. A hierarchical slice map has a top level that includes a count of free blocks in the file system, an upper level that includes a count of free blocks in groups of the slices, an intermediate level that includes a count of the free blocks in sub-groups of the slices, and a bottom level that includes a count of the free blocks in each slice of storage. To find a free block for allocation to a file, the slice map hierarchy is searched in a top-down fashion.

Hierarchical mapping of free blocks of cylinder groups of file systems built on slices of storage and linking of the free blocks

A directory name lookup cache (DNLC) provides a hashed forward mapping for finding the 'child handle' associated with a 'parent handle' and a &#x201c;child name.&#x201d; To provide an efficient reverse lookup capability, a second set of links is added to each cache entry for a &#x201c;child hash list&#x201d; indexed by a hashing of the child handle. For dynamically enabling and disabling the reverse mapping, when a new cache entry is added to its parent hash list, if the reverse mapping is enabled, then the new cache entry is also added to its child hash list; otherwise, the new cache entry is marked to indicate that it is not in any child hash list. To save memory, the parent hash lists and the child hash lists may share hash buckets.

Dynamically configurable reverse DNLC lookup

Markers are established in a data object to provide a means to refer to specified parts of the object. Each marker is established within the object by giving the location and length of the part of the object that is to be marked. The marker continues to mark that part of the object as changes are made elsewhere in the object. As data is received into the cache computer it is stored in a sequence of buffers. A plurality of filters, all executing concurrently, search for different interesting string in the object. Each filter finds its interesting strings and marks them using the markers. The result of filtering data of the object is a marker attribute table identifying each of the markers by the offset and length of the interesting strings located by the filters. Vend time is the time at which the object is streamed out of the cache to a client computer. Before the data is vended, a User Data Filter (UDF) executes a call function which sets up a string substitution table. The substitution table has entries for substitution, including the offset at which to make the substitution and the string to be substituted into the streaming object. A byte counter tracks the outgoing data stream of the object, and whenever the byte count matches an offset of a marker, the length entry in the marker attribute table determines the length of an omitted string, and the substitute string is placed in the outgoing data stream.

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Summit, NJ, United States of America

Michael Scheer