Emc Corporation

Emc IP Holding Company LLC

Sitaram D Pawar

Philippe Armangau

Jean-Pierre Bono

Christopher Alan Seibel

William C Davenport

Yubing Wang

Sairam Veeraswamy

Ivan Basov

Yingchao Zhou

Srinivasa Rao Vempati

Kumari Bijayalaxmi Nanda

Kumar V K H Kanteti

Sorin Faibish

Walter Forrester

Chen Gong

Kevin Xu

Marc A De Souter

Peter C Bixby

Milena Bergant

John Forecast

Jun Guo

Ajay Potnis

Wei Kang

John F Gillono

Pranit Sethi

Soumyadeep Sen

Diane Delgado

Jia Zhai

Kumar Kanteti

Weigang Zhong

Jean Pierre Bono

Kumar Vkh Kanteti

Ashwin B Agrawal

A method for storing data, comprising: obtaining, from a metadata node and by file system client executing on a client application node, a data layout, generating, by the client application node, an error detection value (EDV) for the data stored on the client application node; generating, by a memory hypervisor module executing on the client application node, at least one input/output (I/O) request specifying a location in a storage pool, wherein the location is determined using the data layout; issuing, by the memory hypervisor module, the at least one I/O request to the storage pool, wherein processing the at least one I/O request results in at least a portion of the data being stored at the location; and after issuing the at least one I/O request to the storage pool, transmitting the EDV to the metadata node, wherein the metadata node stores the EDV.

Methods and systems for error detection and correction in a distributed storage system

A method, computer program product, and computing system for receiving a first write request on a front-end computing system within a storage system. The first write request concerns writing a first data portion to a storage array within the storage system. A first log entry is generated within a journal file. The first log entry identifies a first differential storage quantity associated with storing the first data portion in the storage array within the storage system.

Multi-core journal system and method

A method is used in allocating blocks in storage systems. A block allocation request is received for a file of a file system. The block allocation request includes a data block allocation request and an indirect block allocation request. A type of the file is determined. A cylinder group is selected from a set of cylinder groups for allocating an indirect block based on the block allocation request. A set of data blocks is reserved for allocating a data block based on the type of the file.

Allocating blocks in storage systems

A method is used in managing mounting of file systems. A request is received to mount a file system. The request to mount the file system is added in a pending file system mounts queue based on a policy. The file system is mounted in background. Access to the file system is provided before mounting the file system.

Managing mounting of file systems

A method is used in managing caches in storage systems. A set of block entries is reserved in a reserved block entries list of a storage system. The reserved block entries list is associated with a cache of the storage system configured to store data of the storage system. A portion of a memory of the storage system is reserved as the cache. Based on a criterion, a determination is made whether a cache entry is available for use in the cache of the storage system. Based on the determination, a block entry is selected for use from the reserved block entries list.

Managing caches in storage systems

Managing a file system to avoid unnecessary replay of a transaction log. The file system may reside on a non-volatile storage medium having an associated transaction log residing on a non-volatile storage medium, the transaction log including a plurality of log entries, and each log entry representing one or more changes to metadata of the file system. The file system may include a first data structure including a status parameter, a value of which is indicative of whether to replay the transaction log when the file system is initialized. It may be determined whether the one or more changes to metadata represented by each of the plurality of log entries have been written in place in the file system. In response to the determination, the status parameter may be set to a value indicative of the determination.

Managing a file system to avoid unnecessary replay of a transaction log

A method is used in managing updating of metadata of file systems. A reference to a change to metadata of a file of a file system is stored in a global sync list configured to store changes to metadata of a plurality of files of a plurality of file systems. The change to the metadata of the file is stored in a journal upon receiving an I/O request for the file of the file system. The journal includes metadata transactions upon the plurality of files of the plurality of the file system. The change to the metadata of the file of the file system is applied to metadata of the file system organized on a storage device using the reference to the change stored in the global sync list.

Managing updating of metadata of file systems

A method is used in managing delete operations in files of file systems. An indirect data block of a file of a file system is deleted. A parent indirect data block pointing to the indirect data block is removed from a list. The parent indirect data block has been added to the list for flushing contents of the parent indirect data block to a storage device.

Managing delete operations in files of file systems

Systems and methods of managing concurrent log writes to a transaction log are provided. A system may include: a transaction log residing on a non-volatile storage medium for logging metadata transactions of a file system; and a plurality of transaction log buffers, associated with the transaction log, residing in volatile memory. A first write operation may be initiated to write first contents of at least a first of the plurality of transaction log buffers to the transaction log. Concurrently to a performance of the first write operation, a second write operation may be initiated to write second contents of at least a second of the plurality of transaction log buffers to the transaction log.

Managing concurrent write operations to a file system transaction log

A method is used in managing files of file systems. A group transaction record for an indirect data block of a file of a file system is created. The indirect data block of the file includes a set of data blocks of the file. A set of transaction entries is added to the group transaction record. Each transaction entry of the set of transaction entries includes information regarding an operation performed on a data block of the set of data blocks. The group transaction record is stored in a journal. The journal includes metadata transactions upon a plurality of files of a plurality of file systems.

Managing files of file systems

A method is used in managing concurrent I/Os in file systems. A first and second I/O requests are received. The first I/O request is directed to a first portion of a file and the second I/O request is directed to a second portion of the file. A first range lock for the first portion is obtained and a second range lock for the second portion is obtained. The first and second I/O requests are performed concurrently. The second I/O request starts performing I/O on the second portion of the file before the first I/O request finish performing I/O on the first portion of the file.

Managing concurrent I/OS in file systems

A method is used in managing global data caches for file systems. Space is allocated in a volatile memory of a data storage system to a global data cache that is configured to store a set of data objects for a plurality of different file systems. The set of data objects is accessed by the plurality of different file systems. Contents of a file of a file system are stored in a data object in the global data cache upon receiving a write I/O request for the file. A copy of the data object and information for the data object are stored in a persistent journal that is stored in a non-volatile memory of the data storage system. Contents of the file are updated on a storage device based on the data object stored in the global data cache and information stored in the persistent journal.

Managing global data caches for file system

Techniques are presented for keeping only the most commonly-accessed snapshots mounted at any given time, while providing for fast mounting of unmounted snapshots. Techniques are also provided for maintaining separate databases for the snapshots of each primary filesystem in order to minimize locking latency.

Dynamic snapshot mounting

A method is used in managing updating of metadata of file systems. Changes in metadata of a file of a file system are stored in a journal upon receiving an I/O request for the file of the file system. The I/O request results in update of metadata of the file of the file system. The journal includes metadata transactions upon the file system. Changes to metadata of the file are stored in a volatile memory of a data storage system upon receiving subsequent I/O requests resulting in update of metadata of the file of the file system. Metadata of the file of the file system is updated with information derived from metadata changes stored in the journal.

A method is used in managing snapshot in cache-based storage systems. A request to create a snapshot of a data object is received. A portion of the data object is cached in a global cache. The data object is associated with a mapping object. The mapping object manages access to the portion of the data object. A snapshot of the data object is created. A snapshot mapping object is associated with the snapshot of the data object. The snapshot mapping object includes a link to the mapping object. The snapshot mapping object is a version of the mapping object and shares the portion of the data object cached in the global cache.

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Shrewsbury, MA, United States of America

Sitaram D Pawar