Lreflink High Level Design

Introduction

This documentation describes the design of Reflink for Lustre (Lreflink). Reflink is a feature that exists in Btrfs/XFS (not Ext4 or ZFS). When copying a files with cp --reflink=always, it takes advantage copy-on-write in order to do a quick copy of data by merely adding another reference to the shared data blocks, rather than having to read all the data and write it out again.

Client side read/write to Lreflink file is as normal

When client reads/writes to reflink files, it writes or reads in the same way as normal files. However, client needs to provide interfaces to show the Lreflink info of a file.