Asynchronous Directory Operations in CephFS

Monday, February 24, 2020 - 4:00 pm4:30 pm

Jeffrey Layton and Patrick Donnelly, Red Hat


Metadata-heavy workloads are often the bane of networked and clustered filesystems. Directory operations (create and unlink, in particular) usually involve making a synchronous request to a server on the network, which can be very slow.

CephFS however has a novel mechanism for delegating the ability for clients to do certain operations locally. While that mechanism has mostly been used to delegate capabilities on normal files in the past, it's possible to extend this to cover certain types of directory operations as well.

The talk will describe work that is being done to bring asynchronous directory operations to CephFS. It will cover the design and tradeoffs necessary to allow for asynchronous directory operations, discuss the server and client-side infrastructure being added to support it, and what performance gains we expect to gain from this.

Jeffrey Layton, Red Hat

Jeff Layton is a long time Linux kernel developer specializing in network file systems. He has made significant contributions to the kernel's NFS client and server, the CIFS client and the kernel's VFS layer. Recently, he has taken over as the maintainer of the Linux kernel's CephFS driver.

Patrick Donnelly, Red Hat

Patrick Donnelly is a senior software engineer at Red Hat, Inc. currently leading the global development team working on the open-source Ceph distributed file system. Patrick has been a speaker at several events presenting recent work on Ceph, including Cephalocon APAC, various Openstack Summits, CERN, and Vault Linux Storage & Filesystems Conference. In 2016 he completed his Ph.D. in computer science at the University of Notre Dame with a dissertation on the topic of file transfer management in active storage cluster file systems.

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@conference {246532,
author = {Jeffrey Layton and Patrick Donnelly},
title = {Asynchronous Directory Operations in {CephFS}},
year = {2020},
address = {Santa Clara, CA},
publisher = {USENIX Association},
month = feb

Presentation Video