Emc Corporation

Qumulo, Inc.

John Brazel

Max Laier

Justin Husted

Alain Hamel

Aaron Passey

Neal Thomas Fachan

Thomas Scott Urban

Steven Henry Haber

Robert Edward Gebert

Zacharie Lamont Kirsch

Embodiments are directed to managing data in a file system. An object from the file system that has parent objects may be provided. A snapshot in a current epoch may be generated such that the first snapshot may be based on the object and descendants of the object. A coverage set may be provided for the object that references the snapshot and also references each other snapshot that includes the parent objects. Read-only access to a version of the object may be provided based on a correspondence of the version and a snapshot referenced by the coverage set of the object. A coverage engine compares the update to a coverage update epoch (cue) associated with the parent objects. The coverage engine updates coverage sets of the parent objects based on grandparents of the object.

Managing per object snapshot coverage in filesystems

Various embodiments are directed towards enabling data writes utilizing a node cache and a logstore stored on a stable storage device. A client device may send data to a node for writing to a parent file. The node may cache the received data prior to writing the data to the parent file. Caching the received data may comprise adding the received data to a node cache and to a logstore. In one embodiment, the node cache may include a coalescer that combines data from a plurality of data writes from the client device to the node prior to writing to the parent file. In some embodiments, the logstore may be mirrored logstore on one or more stable storage devices. The parent file may periodically be updated from the node cache data. After the parent file is updated, the node cache data and the logstore data may be purged.

Recovery and flush of endurant cache

Endurant cache

The various embodiments are directed towards enabling a versioned coalescer to defer when data blocks cached in unstable storage may be flushed to stable storage. In at least one of the various embodiments, deferring the flushing of cached data blocks until they are read may avoid having to periodically suspend cache operations to flush all cached data from unstable storage to stable storage. In at least one of the various embodiments, if data blocks may be written, a versioned coalescer may cache the data blocks in a high-performance node cache that may be dedicated to a node in a distributed file system. Further, if a process requires a snapshot of at least a portion of the file system a versioned coalescer may examine the node caches for each node. If a node cache contains relevant data blocks the versioned coalescer may insert a snapshot sentinel into the node cache.

Versioned coalescer

Growing community of inventors

Seattle, WA, United States of America

John Brazel