LeoFS Overview

LeoFS is a highly scalable, fault-tolerant distributed file system (DFS) for the Web. LeoFS is the leading DFS and offers a number of unique benefits to users.

LeoFS provides High Cost Performance Ratio. It allows you to build LeoFS clusters using commodity hardware on top of the Linux operating system. LeoFS will provide very good performance even on commodity hardware. LeoFS will require a smaller cluster than other storage to achieve the same performance. LeoFS is also very easy to setup and to operate.

LeoFS provides High Reliability thanks to its great design on top of the Erlang/OTP capabilities. Erlang/OTP is known for being used in production systems for years with a solid nine nines (99.9999999%) availability, and LeoFS is no exception. A LeoFS system will stay up regardless of software errors or hardware failures happening inside the cluster.

LeoFS provides High Scalability. Adding and removing nodes is simple and quick, allowing you to react swiftly when your needs change. A LeoFS cluster can be thought as elastic storage that you can stretch as much and as often as you need.


LeoFS consists of 3 applications - “Leo Storage”, “Leo Gateway” and “Leo Manager” which depend on Erlang.

Leo Gateway handles http-request and http-response from any clients when using REST-API OR S3-API. Also, Gateway is already built in the object-cache mechanism (memory cache and disc cache).

Leo Storage handles GET, PUT and DELETE objects as well as metadata, Also Leo Storage has replicator, recoverer and queueing mechanism for keep running and keep consistency.

Leo Manager always monitors Leo Gateway(s) and Leo Storage(s). Main monitoring status are node-status and RING(logical routing-table) checksum for keep running and keep consistency.

The detail document is here.


  • LeoFS aims to provide the following advantages:
    • HIGH Cost Performance Ratio
      • Fast - Over 200MB/sec in a 10GE network
      • A lower cost than other storage
      • Easy management and easy operation
    • HIGH Reliability
      • Nine nines - 99.9999999% availability
    • High Scalability
      • Build a huge cluster at low cost


  • DONE - 0.12 (Oct 2012 - Jan 2013)
    • Large Object Support (incl.Streaming/Multi-part/Range requests)

    • Web GUI-Console (LeoTamer - Optional)
      • Cluster manager/monitor
      • Log Analysis/Search
  • DONE - 0.14 (Feb 2013 - Sep)
    • Multi-layer Cache (Using SSD)

    • Rack aware replica placement

    • Web GUI Console (Option)
      • Support whole LeoFS Manager’s commands
  • 0.16 (Oct 2013)
    • Increase compatibility S3-APIs#4
      • the bucket ACLs
    • Web GUI Console (Option)
      • Support whole LeoFS Manager’s commands
  • 1.0 (Nov 2013 - Dec)
    • Multi Data Center Replication

    • Increase compatibility S3-APIs#5
      • Other bucket operations
    • QoS System Phase-1 (LeoInsight - Option)
      • Support statistics/analyzer
  • 1.2 (Jan 2014 - Apr)
    • OpenStack Integration
      • Support for OpenStack Swift-API
    • Increase compatibility S3-APIs#6
      • Objects Expiration into the bucket
      • Versioning
    • Job Scheduler on the Manager
      • Support auto-compaction
    • QoS System Phase-2 (LeoInsight - Option)
      • Support notifier
    • Web GUI Console (Option)
      • LeoInsight(QoS) Integration
      • Support Log analysis/search

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