Vmware, Inc.

Sriram Patil

Wenguang Wang

Abhay Kumar Jain

Richard Paul Spillane

Hong Li

Enning Xiang

Asit Desai

Ye Zhang

Pranay Singh

Nitin Rastogi

Eric Shannon Knauft

Junlong Gao

Xiang Yu

Zhaohui Guo

Wangping He

Example methods and systems for accessing data in a log-structured file system having a plurality of snapshots of storage objects backed by a first-level copy-on-write (COW) B+ tree data structure and a plurality of second-level B+ tree data structures have been disclosed. One example method includes obtaining a first first-level mapping associated with a first snapshot from the plurality of snapshots based on a first logical block address, wherein each of the plurality of snapshots corresponds to each of the plurality of second-level B+ tree data structures, identifying a first second-level B+ tree data structure corresponding to one of the plurality of snapshots based on the first first-level mapping, obtaining a first second-level mapping based on the first logical block address in the first second-level B+ tree data structure, obtaining a first physical block address based on the first second-level mapping, and accessing data at the first physical block address.

Two-level logical to physical mapping mechanism in a log-structured file system

A method for managing replication of cloned files is provided. Embodiments include determining, at a source system, that a first file has been cloned to create a second file. Embodiments include sending, from the source system to a replica system, an address of the first extent and an indication that a status of the first extent has changed from non-cloned to cloned. Embodiments include changing, at the replica system, a status of a second extent associated with a replica of the first file on the replica system from non-cloned to cloned and creating a mapping of the address of the first extent to an address of the second extent on the replica system. Embodiments include creating, at the replica system, a replica of the second file comprising a reference to the address of the second extent on the replica system.

Efficient replication of file clones

Techniques for efficiently managing a file clone from a filesystem which supports efficient volume snapshots are provided. In some embodiments, a system may receive an instruction to remove the file clone from the filesystem. The file clone may be a point-in-time copy of metadata of an original file. The system may further&#x2014;for a file map entry in a filesystem tree associated with the file clone, the file map entry indicating a data block&#x2014;decrement a reference count in a reference count entry associated with the file map entry. The reference count entry may be stored in the filesystem tree according to a key and the key may comprise an identification of the original file. The system may further reclaim the data block in a storage system when the reference count is zero.

Embedded reference counts for file clones

Techniques for improving the read performance of an LFS-based storage system that supports COW snapshotting are provided. In one set of embodiments, the storage system can implement an intermediate map for each storage object in the system that is keyed by a composite key consisting of snapshot identifier (major key) and LBA (minor key). With this approach, contiguous logical block addresses (LBAs) of a storage object or its snapshots will map to contiguous &#x3c;Snapshot ID, LBA&#x3e;-to-PBA mappings in the storage object's intermediate map, resulting in good spatial locality for those LBAs and robust read performance.

Read performance of log-structured file system (LFS)-based storage systems that support copy-on-write (COW) snapshotting

System and method for automatic remediation for a distributed file system uses a file system (FS) remediation module running in a cluster management server and FS remediation agents running in a cluster of host computers. The FS remediation module monitors the cluster of host computers for related events. When a first file system service (FSS)-impacting event is detected, a cluster-level remediation action is executed at the cluster management server by the FS remediation module in response to the detected first FSS-impacting event. When a second FSS-impacting event is detected, a host-level remediation action is executed at one or more of the host computers in the cluster by the FS remediation agents in response to the detected second FSS-impacting event.

File service auto-remediation in storage systems

System and method for writing updated versions of a configuration data file for a distributed file system in a storage system uses a directory renaming operation to write a new updated version of the configuration data file using the latest version of the configuration data file and a target directory. After the latest version of the configuration data file is modified by a particular host computer in the storage system, the modified configuration data file is written to a temporary file. The directory naming operation is then initiated on the temporary file to change the directory for the temporary file to the target directory. If the directory renaming operation has failed, a retry is performed by the particular host computer to write the new updated version of the configuration data file using a new latest version and a new target directory.

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San Jose, CA, United States of America

Sriram Patil