Lustre Internals Documentation Update

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  • Incremental updating of Lustre internals documentation
  • Near term focus is material in support of upcoming Introduction To Lustre Development webinar
  • The available time for those with Lustre internals knowledge is limited, maximizing the efficiency of their efforts is a priority.


  • Updates are moving to Category:Internals and pages with the Internals category in order to better facilitate linking and incremental updating.
  • For the near future full documents (ULFI, LIAGI) are being moved over to a single wiki page. Adding subpage support to MediaWiki is a topic for the next LOWG call and may provide some flexibility there moving forward.
  • Lustre internals is a regular topic on the Lustre Working Group calls, and the Lustre Internals Documentation Update project is discussed regularly on the Working Group calls. Please join us.


  • LIAGI (Lustre Internals: A Gentle Introduction)
  • ULFI (Understanding Lustre Filesystem Internals)



  • Migrate ULFI from shared document to wiki to facilitate targeted linking and updating. (in-progress)
  • Migrate LIAGI from web to wiki
  • Update Subsystem Map for current subsystems
  • Add Layered Object wiki page, reference source-tree clio.txt and LIAGI resources
  • Create OSD internals page and reference source-tree osd-api.txt


  • Work with developers to identify areas that need more work.
  • Update wiki PtlRPC page and reference PtlRPC ULFI chapter as well as Lustre Protocol Document
  • Generate Doxygen comments from current source tree and put on web
  • Review Doxygen comments in code base and find methods to reference them from wiki
  • Keep Lustre_Internals wiki page?
  • Migrate Lustre Protocol Document to wiki?



Feedback from discussions with community members on updating Lustre internals documentation in general:

  • Top-down versus bottom-up approach
    • Differing viewpoints on this. Possible to find way to address both?
  • Separate documents (e.g. Understanding Lustre Filesystem Internals document) versus documentation in the code (e.g. Doxygen)
    • Possible to incrementally expand and update both, balance what's in them, and have them mutually reference?


Lustre Protocol Documentation


Sequoia and the ZFS OSD (LUG2013)

IntelĀ® Lustre* File Level Replication (LUG2014)

Distributed Name Space Phase I (LUG2013)

Lustre & Kerberos: in theory and in practice (LUG2015)

Documentation in Lustre Tree

Doxygen Code Documentation

Overview of the Lustre Client I/O (CLIO) subsystem


  • LFSCK master slave design
  • Object traversal design reference

Lock Ordering

/* dot input file for lock-ordering diagram */

Overview of the Lustre Object Storage Device API

Overview of Dynamic LNet Configuration

Lustre versioning

Old Wiki Architectural Documents

Page Comments
Architecture - Backup
Architecture - CROW
Architecture - CTDB with Lustre
Architecture - Caching OSS
Architecture - Changelogs
Architecture - Changelogs 1.6
Architecture - Client Cleanup
Architecture - Clustered Metadata
Architecture - Commit on Share
Architecture - Cuts
Architecture - DMU OSD
Architecture - DMU Zerocopy
Architecture - End-to-end Checksumming
Architecture - Epochs
Architecture - External File Locking
Architecture - FIDs on OST
Architecture - Feature FS Replication
Architecture - Fileset
Architecture - Flash Cache
Architecture - Free Space Management
Architecture - GNS
Architecture - HSM No useful information
Architecture - HSM Migration
Architecture - HSM and Cache No useful information
Architecture - IO system
Architecture - Interoperability 1.6 1.8 2.0
Architecture - Interoperability fids zfs
Architecture - LRE Images
Architecture - Libcfs
Architecture - Llog over OSD
Architecture - Lustre DLDs
Architecture - Lustre HLDs
Architecture - Lustre Logging API
Architecture - MDS-on-DMU
Architecture - MDS striping format
Architecture - MPI IO and NetCDF
Architecture - MPI LND
Architecture - Metadata API
Architecture - Migration (1)
Architecture - Migration (2)
Architecture - Multiple Interfaces For LNET
Architecture - Network Request Scheduler
Architecture - New Metadata API
Architecture - OSS-on-DMU
Architecture - Open by fid
Architecture - PAG
Architecture - Pools of targets
Architecture - Profiling Tools for IO
Architecture - Proxy Cache
Architecture - Punch and Extent Migration
Architecture - Punch and Extent Migration Requirements
Architecture - Recovery Failures
Architecture - Request Redirection
Architecture - Scalable Pinger
Architecture - Security
Architecture - Server Network Striping
Architecture - Simple Space Balance Migration
Architecture - Simplified Interoperation
Architecture - Space Manager
Architecture - Sub Tree Locks
Architecture - User Level Access
Architecture - User Level OSS
Architecture - Userspace Servers
Architecture - Version Based Recovery
Architecture - Wide Striping
Architecture - Wire Level Protocol
Architecture - Write Back Cache
Architecture - Writing Architecture Documents
Architecture - ZFS TinyZAP
Architecture - ZFS for Lustre
Architecture - ZFS large dnodes
Architecture Descriptions

Old Site Lustre Internals Documentation Area


Brief descriptions of Lustre concepts, objects and major components indexed in various ways.

Lustre Internals: A Gentle Introduction

Subsystem Map

TODO: Generate new version of