You can not select more than 25 topics Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
 
 
 
 

1731 lines
38 KiB

<!doctype html>
<html lang="en" class="no-js">
<head>
<meta charset="utf-8">
<meta name="viewport" content="width=device-width,initial-scale=1">
<meta name="description" content="mergerfs - a featureful union filesystem">
<link rel="canonical" href="https://trapexit.github.io/mergerfs/">
<link rel="next" href="quickstart/">
<link rel="icon" href="assets/images/favicon.png">
<meta name="generator" content="mkdocs-1.6.1, mkdocs-material-9.5.49">
<title>mergerfs</title>
<link rel="stylesheet" href="assets/stylesheets/main.6f8fc17f.min.css">
<link rel="stylesheet" href="assets/stylesheets/palette.06af60db.min.css">
<link rel="preconnect" href="https://fonts.gstatic.com" crossorigin>
<link rel="stylesheet" href="https://fonts.googleapis.com/css?family=Roboto:300,300i,400,400i,700,700i%7CRoboto+Mono:400,400i,700,700i&display=fallback">
<style>:root{--md-text-font:"Roboto";--md-code-font:"Roboto Mono"}</style>
<script>__md_scope=new URL(".",location),__md_hash=e=>[...e].reduce(((e,_)=>(e<<5)-e+_.charCodeAt(0)),0),__md_get=(e,_=localStorage,t=__md_scope)=>JSON.parse(_.getItem(t.pathname+"."+e)),__md_set=(e,_,t=localStorage,a=__md_scope)=>{try{t.setItem(a.pathname+"."+e,JSON.stringify(_))}catch(e){}}</script>
</head>
<body dir="ltr" data-md-color-scheme="default" data-md-color-primary="indigo" data-md-color-accent="indigo">
<input class="md-toggle" data-md-toggle="drawer" type="checkbox" id="__drawer" autocomplete="off">
<input class="md-toggle" data-md-toggle="search" type="checkbox" id="__search" autocomplete="off">
<label class="md-overlay" for="__drawer"></label>
<div data-md-component="skip">
<a href="#mergerfs-a-featureful-union-filesystem" class="md-skip">
Skip to content
</a>
</div>
<div data-md-component="announce">
</div>
<header class="md-header md-header--shadow" data-md-component="header">
<nav class="md-header__inner md-grid" aria-label="Header">
<a href="." title="mergerfs" class="md-header__button md-logo" aria-label="mergerfs" data-md-component="logo">
<img src="logo.jpeg" alt="logo">
</a>
<label class="md-header__button md-icon" for="__drawer">
<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 24 24"><path d="M3 6h18v2H3zm0 5h18v2H3zm0 5h18v2H3z"/></svg>
</label>
<div class="md-header__title" data-md-component="header-title">
<div class="md-header__ellipsis">
<div class="md-header__topic">
<span class="md-ellipsis">
mergerfs
</span>
</div>
<div class="md-header__topic" data-md-component="header-topic">
<span class="md-ellipsis">
Home
</span>
</div>
</div>
</div>
<form class="md-header__option" data-md-component="palette">
<input class="md-option" data-md-color-media="(prefers-color-scheme)" data-md-color-scheme="default" data-md-color-primary="indigo" data-md-color-accent="indigo" aria-label="Switch to light mode" type="radio" name="__palette" id="__palette_0">
<label class="md-header__button md-icon" title="Switch to light mode" for="__palette_1" hidden>
<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 24 24"><path d="m14.3 16-.7-2h-3.2l-.7 2H7.8L11 7h2l3.2 9zM20 8.69V4h-4.69L12 .69 8.69 4H4v4.69L.69 12 4 15.31V20h4.69L12 23.31 15.31 20H20v-4.69L23.31 12zm-9.15 3.96h2.3L12 9z"/></svg>
</label>
<input class="md-option" data-md-color-media="(prefers-color-scheme: light)" data-md-color-scheme="default" data-md-color-primary="indigo" data-md-color-accent="indigo" aria-label="Switch to dark mode" type="radio" name="__palette" id="__palette_1">
<label class="md-header__button md-icon" title="Switch to dark mode" for="__palette_2" hidden>
<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 24 24"><path d="M12 8a4 4 0 0 0-4 4 4 4 0 0 0 4 4 4 4 0 0 0 4-4 4 4 0 0 0-4-4m0 10a6 6 0 0 1-6-6 6 6 0 0 1 6-6 6 6 0 0 1 6 6 6 6 0 0 1-6 6m8-9.31V4h-4.69L12 .69 8.69 4H4v4.69L.69 12 4 15.31V20h4.69L12 23.31 15.31 20H20v-4.69L23.31 12z"/></svg>
</label>
<input class="md-option" data-md-color-media="(prefers-color-scheme: dark)" data-md-color-scheme="slate" data-md-color-primary="indigo" data-md-color-accent="indigo" aria-label="Switch to system preference" type="radio" name="__palette" id="__palette_2">
<label class="md-header__button md-icon" title="Switch to system preference" for="__palette_0" hidden>
<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 24 24"><path d="M12 18c-.89 0-1.74-.2-2.5-.55C11.56 16.5 13 14.42 13 12s-1.44-4.5-3.5-5.45C10.26 6.2 11.11 6 12 6a6 6 0 0 1 6 6 6 6 0 0 1-6 6m8-9.31V4h-4.69L12 .69 8.69 4H4v4.69L.69 12 4 15.31V20h4.69L12 23.31 15.31 20H20v-4.69L23.31 12z"/></svg>
</label>
</form>
<script>var palette=__md_get("__palette");if(palette&&palette.color){if("(prefers-color-scheme)"===palette.color.media){var media=matchMedia("(prefers-color-scheme: light)"),input=document.querySelector(media.matches?"[data-md-color-media='(prefers-color-scheme: light)']":"[data-md-color-media='(prefers-color-scheme: dark)']");palette.color.media=input.getAttribute("data-md-color-media"),palette.color.scheme=input.getAttribute("data-md-color-scheme"),palette.color.primary=input.getAttribute("data-md-color-primary"),palette.color.accent=input.getAttribute("data-md-color-accent")}for(var[key,value]of Object.entries(palette.color))document.body.setAttribute("data-md-color-"+key,value)}</script>
<label class="md-header__button md-icon" for="__search">
<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 24 24"><path d="M9.5 3A6.5 6.5 0 0 1 16 9.5c0 1.61-.59 3.09-1.56 4.23l.27.27h.79l5 5-1.5 1.5-5-5v-.79l-.27-.27A6.52 6.52 0 0 1 9.5 16 6.5 6.5 0 0 1 3 9.5 6.5 6.5 0 0 1 9.5 3m0 2C7 5 5 7 5 9.5S7 14 9.5 14 14 12 14 9.5 12 5 9.5 5"/></svg>
</label>
<div class="md-search" data-md-component="search" role="dialog">
<label class="md-search__overlay" for="__search"></label>
<div class="md-search__inner" role="search">
<form class="md-search__form" name="search">
<input type="text" class="md-search__input" name="query" aria-label="Search" placeholder="Search" autocapitalize="off" autocorrect="off" autocomplete="off" spellcheck="false" data-md-component="search-query" required>
<label class="md-search__icon md-icon" for="__search">
<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 24 24"><path d="M9.5 3A6.5 6.5 0 0 1 16 9.5c0 1.61-.59 3.09-1.56 4.23l.27.27h.79l5 5-1.5 1.5-5-5v-.79l-.27-.27A6.52 6.52 0 0 1 9.5 16 6.5 6.5 0 0 1 3 9.5 6.5 6.5 0 0 1 9.5 3m0 2C7 5 5 7 5 9.5S7 14 9.5 14 14 12 14 9.5 12 5 9.5 5"/></svg>
<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 24 24"><path d="M20 11v2H8l5.5 5.5-1.42 1.42L4.16 12l7.92-7.92L13.5 5.5 8 11z"/></svg>
</label>
<nav class="md-search__options" aria-label="Search">
<a href="javascript:void(0)" class="md-search__icon md-icon" title="Share" aria-label="Share" data-clipboard data-clipboard-text="" data-md-component="search-share" tabindex="-1">
<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 24 24"><path d="M18 16.08c-.76 0-1.44.3-1.96.77L8.91 12.7c.05-.23.09-.46.09-.7s-.04-.47-.09-.7l7.05-4.11c.54.5 1.25.81 2.04.81a3 3 0 0 0 3-3 3 3 0 0 0-3-3 3 3 0 0 0-3 3c0 .24.04.47.09.7L8.04 9.81C7.5 9.31 6.79 9 6 9a3 3 0 0 0-3 3 3 3 0 0 0 3 3c.79 0 1.5-.31 2.04-.81l7.12 4.15c-.05.21-.08.43-.08.66 0 1.61 1.31 2.91 2.92 2.91s2.92-1.3 2.92-2.91A2.92 2.92 0 0 0 18 16.08"/></svg>
</a>
<button type="reset" class="md-search__icon md-icon" title="Clear" aria-label="Clear" tabindex="-1">
<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 24 24"><path d="M19 6.41 17.59 5 12 10.59 6.41 5 5 6.41 10.59 12 5 17.59 6.41 19 12 13.41 17.59 19 19 17.59 13.41 12z"/></svg>
</button>
</nav>
</form>
<div class="md-search__output">
<div class="md-search__scrollwrap" tabindex="0" data-md-scrollfix>
<div class="md-search-result" data-md-component="search-result">
<div class="md-search-result__meta">
Initializing search
</div>
<ol class="md-search-result__list" role="presentation"></ol>
</div>
</div>
</div>
</div>
</div>
<div class="md-header__source">
<a href="https://github.com/trapexit/mergerfs" title="Go to repository" class="md-source" data-md-component="source">
<div class="md-source__icon md-icon">
<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 448 512"><!--! Font Awesome Free 6.7.1 by @fontawesome - https://fontawesome.com License - https://fontawesome.com/license/free (Icons: CC BY 4.0, Fonts: SIL OFL 1.1, Code: MIT License) Copyright 2024 Fonticons, Inc.--><path d="M439.55 236.05 244 40.45a28.87 28.87 0 0 0-40.81 0l-40.66 40.63 51.52 51.52c27.06-9.14 52.68 16.77 43.39 43.68l49.66 49.66c34.23-11.8 61.18 31 35.47 56.69-26.49 26.49-70.21-2.87-56-37.34L240.22 199v121.85c25.3 12.54 22.26 41.85 9.08 55a34.34 34.34 0 0 1-48.55 0c-17.57-17.6-11.07-46.91 11.25-56v-123c-20.8-8.51-24.6-30.74-18.64-45L142.57 101 8.45 235.14a28.86 28.86 0 0 0 0 40.81l195.61 195.6a28.86 28.86 0 0 0 40.8 0l194.69-194.69a28.86 28.86 0 0 0 0-40.81"/></svg>
</div>
<div class="md-source__repository">
mergerfs
</div>
</a>
</div>
</nav>
</header>
<div class="md-container" data-md-component="container">
<main class="md-main" data-md-component="main">
<div class="md-main__inner md-grid">
<div class="md-sidebar md-sidebar--primary" data-md-component="sidebar" data-md-type="navigation" >
<div class="md-sidebar__scrollwrap">
<div class="md-sidebar__inner">
<nav class="md-nav md-nav--primary" aria-label="Navigation" data-md-level="0">
<label class="md-nav__title" for="__drawer">
<a href="." title="mergerfs" class="md-nav__button md-logo" aria-label="mergerfs" data-md-component="logo">
<img src="logo.jpeg" alt="logo">
</a>
mergerfs
</label>
<div class="md-nav__source">
<a href="https://github.com/trapexit/mergerfs" title="Go to repository" class="md-source" data-md-component="source">
<div class="md-source__icon md-icon">
<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 448 512"><!--! Font Awesome Free 6.7.1 by @fontawesome - https://fontawesome.com License - https://fontawesome.com/license/free (Icons: CC BY 4.0, Fonts: SIL OFL 1.1, Code: MIT License) Copyright 2024 Fonticons, Inc.--><path d="M439.55 236.05 244 40.45a28.87 28.87 0 0 0-40.81 0l-40.66 40.63 51.52 51.52c27.06-9.14 52.68 16.77 43.39 43.68l49.66 49.66c34.23-11.8 61.18 31 35.47 56.69-26.49 26.49-70.21-2.87-56-37.34L240.22 199v121.85c25.3 12.54 22.26 41.85 9.08 55a34.34 34.34 0 0 1-48.55 0c-17.57-17.6-11.07-46.91 11.25-56v-123c-20.8-8.51-24.6-30.74-18.64-45L142.57 101 8.45 235.14a28.86 28.86 0 0 0 0 40.81l195.61 195.6a28.86 28.86 0 0 0 40.8 0l194.69-194.69a28.86 28.86 0 0 0 0-40.81"/></svg>
</div>
<div class="md-source__repository">
mergerfs
</div>
</a>
</div>
<ul class="md-nav__list" data-md-scrollfix>
<li class="md-nav__item md-nav__item--active">
<input class="md-nav__toggle md-toggle" type="checkbox" id="__toc">
<label class="md-nav__link md-nav__link--active" for="__toc">
<span class="md-ellipsis">
Home
</span>
<span class="md-nav__icon md-icon"></span>
</label>
<a href="." class="md-nav__link md-nav__link--active">
<span class="md-ellipsis">
Home
</span>
</a>
<nav class="md-nav md-nav--secondary" aria-label="Table of contents">
<label class="md-nav__title" for="__toc">
<span class="md-nav__icon md-icon"></span>
Table of contents
</label>
<ul class="md-nav__list" data-md-component="toc" data-md-scrollfix>
<li class="md-nav__item">
<a href="#features" class="md-nav__link">
<span class="md-ellipsis">
Features
</span>
</a>
</li>
<li class="md-nav__item">
<a href="#non-features" class="md-nav__link">
<span class="md-ellipsis">
Non-features
</span>
</a>
</li>
<li class="md-nav__item">
<a href="#how-it-works" class="md-nav__link">
<span class="md-ellipsis">
How it works
</span>
</a>
<nav class="md-nav" aria-label="How it works">
<ul class="md-nav__list">
<li class="md-nav__item">
<a href="#visualization" class="md-nav__link">
<span class="md-ellipsis">
Visualization
</span>
</a>
</li>
</ul>
</nav>
</li>
</ul>
</nav>
</li>
<li class="md-nav__item">
<a href="quickstart/" class="md-nav__link">
<span class="md-ellipsis">
QuickStart
</span>
</a>
</li>
<li class="md-nav__item md-nav__item--nested">
<input class="md-nav__toggle md-toggle " type="checkbox" id="__nav_3" >
<label class="md-nav__link" for="__nav_3" id="__nav_3_label" tabindex="0">
<span class="md-ellipsis">
Installation
</span>
<span class="md-nav__icon md-icon"></span>
</label>
<nav class="md-nav" data-md-level="1" aria-labelledby="__nav_3_label" aria-expanded="false">
<label class="md-nav__title" for="__nav_3">
<span class="md-nav__icon md-icon"></span>
Installation
</label>
<ul class="md-nav__list" data-md-scrollfix>
<li class="md-nav__item">
<a href="setup/installation/" class="md-nav__link">
<span class="md-ellipsis">
Installation
</span>
</a>
</li>
<li class="md-nav__item">
<a href="setup/upgrade/" class="md-nav__link">
<span class="md-ellipsis">
Upgrade
</span>
</a>
</li>
<li class="md-nav__item">
<a href="setup/build/" class="md-nav__link">
<span class="md-ellipsis">
Build
</span>
</a>
</li>
</ul>
</nav>
</li>
<li class="md-nav__item md-nav__item--nested">
<input class="md-nav__toggle md-toggle " type="checkbox" id="__nav_4" >
<label class="md-nav__link" for="__nav_4" id="__nav_4_label" tabindex="0">
<span class="md-ellipsis">
Config
</span>
<span class="md-nav__icon md-icon"></span>
</label>
<nav class="md-nav" data-md-level="1" aria-labelledby="__nav_4_label" aria-expanded="false">
<label class="md-nav__title" for="__nav_4">
<span class="md-nav__icon md-icon"></span>
Config
</label>
<ul class="md-nav__list" data-md-scrollfix>
<li class="md-nav__item">
<a href="config/terminology/" class="md-nav__link">
<span class="md-ellipsis">
Terminology
</span>
</a>
</li>
<li class="md-nav__item">
<a href="config/options/" class="md-nav__link">
<span class="md-ellipsis">
Options
</span>
</a>
</li>
<li class="md-nav__item">
<a href="config/deprecated_options/" class="md-nav__link">
<span class="md-ellipsis">
Deprecated Options
</span>
</a>
</li>
<li class="md-nav__item">
<a href="config/branches/" class="md-nav__link">
<span class="md-ellipsis">
branches
</span>
</a>
</li>
<li class="md-nav__item">
<a href="config/functions_categories_and_policies/" class="md-nav__link">
<span class="md-ellipsis">
functions, categories and policies
</span>
</a>
</li>
<li class="md-nav__item">
<a href="config/func_readdir/" class="md-nav__link">
<span class="md-ellipsis">
func.readdir
</span>
</a>
</li>
<li class="md-nav__item">
<a href="config/rename_and_link/" class="md-nav__link">
<span class="md-ellipsis">
rename and link
</span>
</a>
</li>
<li class="md-nav__item">
<a href="config/cache/" class="md-nav__link">
<span class="md-ellipsis">
caching
</span>
</a>
</li>
<li class="md-nav__item">
<a href="config/readahead/" class="md-nav__link">
<span class="md-ellipsis">
readahead
</span>
</a>
</li>
<li class="md-nav__item">
<a href="config/inodecalc/" class="md-nav__link">
<span class="md-ellipsis">
inodecalc
</span>
</a>
</li>
<li class="md-nav__item">
<a href="config/threads/" class="md-nav__link">
<span class="md-ellipsis">
threads
</span>
</a>
</li>
<li class="md-nav__item">
<a href="config/pin-threads/" class="md-nav__link">
<span class="md-ellipsis">
pin-threads
</span>
</a>
</li>
<li class="md-nav__item">
<a href="config/link_cow/" class="md-nav__link">
<span class="md-ellipsis">
link_cow
</span>
</a>
</li>
<li class="md-nav__item">
<a href="config/fuse_msg_size/" class="md-nav__link">
<span class="md-ellipsis">
fuse_msg_size
</span>
</a>
</li>
<li class="md-nav__item">
<a href="config/follow-symlinks/" class="md-nav__link">
<span class="md-ellipsis">
follow-symlinks
</span>
</a>
</li>
<li class="md-nav__item">
<a href="config/link-exdev/" class="md-nav__link">
<span class="md-ellipsis">
link-exdev
</span>
</a>
</li>
<li class="md-nav__item">
<a href="config/rename-exdev/" class="md-nav__link">
<span class="md-ellipsis">
rename-exdev
</span>
</a>
</li>
<li class="md-nav__item">
<a href="config/symlinkify/" class="md-nav__link">
<span class="md-ellipsis">
symlinkify
</span>
</a>
</li>
<li class="md-nav__item">
<a href="config/nullrw/" class="md-nav__link">
<span class="md-ellipsis">
nullrw
</span>
</a>
</li>
<li class="md-nav__item">
<a href="config/xattr/" class="md-nav__link">
<span class="md-ellipsis">
xattr
</span>
</a>
</li>
<li class="md-nav__item">
<a href="config/nfsopenhack/" class="md-nav__link">
<span class="md-ellipsis">
nfsopenhack
</span>
</a>
</li>
<li class="md-nav__item">
<a href="config/statfs/" class="md-nav__link">
<span class="md-ellipsis">
statfs / statvfs
</span>
</a>
</li>
<li class="md-nav__item">
<a href="config/flush-on-close/" class="md-nav__link">
<span class="md-ellipsis">
flush-on-close
</span>
</a>
</li>
<li class="md-nav__item">
<a href="config/export-support/" class="md-nav__link">
<span class="md-ellipsis">
export-support
</span>
</a>
</li>
</ul>
</nav>
</li>
<li class="md-nav__item">
<a href="error_handling/" class="md-nav__link">
<span class="md-ellipsis">
Error Handling
</span>
</a>
</li>
<li class="md-nav__item">
<a href="runtime_interfaces/" class="md-nav__link">
<span class="md-ellipsis">
Runtime Interfaces
</span>
</a>
</li>
<li class="md-nav__item">
<a href="remote_filesystems/" class="md-nav__link">
<span class="md-ellipsis">
Remote Filesystems
</span>
</a>
</li>
<li class="md-nav__item">
<a href="tips_notes/" class="md-nav__link">
<span class="md-ellipsis">
Tips and Notes
</span>
</a>
</li>
<li class="md-nav__item">
<a href="known_issues_bugs/" class="md-nav__link">
<span class="md-ellipsis">
Known Issues and Bugs
</span>
</a>
</li>
<li class="md-nav__item">
<a href="project_comparisons/" class="md-nav__link">
<span class="md-ellipsis">
Project Comparisons
</span>
</a>
</li>
<li class="md-nav__item">
<a href="performance/" class="md-nav__link">
<span class="md-ellipsis">
Tweaking Performance
</span>
</a>
</li>
<li class="md-nav__item">
<a href="benchmarking/" class="md-nav__link">
<span class="md-ellipsis">
Benchmarking
</span>
</a>
</li>
<li class="md-nav__item">
<a href="tooling/" class="md-nav__link">
<span class="md-ellipsis">
Tooling
</span>
</a>
</li>
<li class="md-nav__item md-nav__item--nested">
<input class="md-nav__toggle md-toggle " type="checkbox" id="__nav_14" >
<label class="md-nav__link" for="__nav_14" id="__nav_14_label" tabindex="0">
<span class="md-ellipsis">
FAQ
</span>
<span class="md-nav__icon md-icon"></span>
</label>
<nav class="md-nav" data-md-level="1" aria-labelledby="__nav_14_label" aria-expanded="false">
<label class="md-nav__title" for="__nav_14">
<span class="md-nav__icon md-icon"></span>
FAQ
</label>
<ul class="md-nav__list" data-md-scrollfix>
<li class="md-nav__item">
<a href="faq/reliability_and_scalability/" class="md-nav__link">
<span class="md-ellipsis">
Reliability and Scalability
</span>
</a>
</li>
<li class="md-nav__item">
<a href="faq/usage_and_functionality/" class="md-nav__link">
<span class="md-ellipsis">
Usage and Functionality
</span>
</a>
</li>
<li class="md-nav__item">
<a href="faq/configuration_and_policies/" class="md-nav__link">
<span class="md-ellipsis">
Configuration and Policies
</span>
</a>
</li>
<li class="md-nav__item">
<a href="faq/compatibility_and_integration/" class="md-nav__link">
<span class="md-ellipsis">
Compatibility and Integration
</span>
</a>
</li>
<li class="md-nav__item">
<a href="faq/recommendations_and_warnings/" class="md-nav__link">
<span class="md-ellipsis">
Recommendations and Warnings
</span>
</a>
</li>
<li class="md-nav__item">
<a href="faq/technical_behavior_and_limitations/" class="md-nav__link">
<span class="md-ellipsis">
Technical Behavior and Limitations
</span>
</a>
</li>
<li class="md-nav__item">
<a href="faq/limit_drive_spinup/" class="md-nav__link">
<span class="md-ellipsis">
Limiting drive spinup
</span>
</a>
</li>
</ul>
</nav>
</li>
<li class="md-nav__item">
<a href="related_projects/" class="md-nav__link">
<span class="md-ellipsis">
Related Projects
</span>
</a>
</li>
<li class="md-nav__item">
<a href="media_and_publicity/" class="md-nav__link">
<span class="md-ellipsis">
Media and Publicity
</span>
</a>
</li>
<li class="md-nav__item">
<a href="support/" class="md-nav__link">
<span class="md-ellipsis">
Support
</span>
</a>
</li>
<li class="md-nav__item">
<a href="sponsorship_and_donations/" class="md-nav__link">
<span class="md-ellipsis">
Sponsorship and Donations
</span>
</a>
</li>
</ul>
</nav>
</div>
</div>
</div>
<div class="md-sidebar md-sidebar--secondary" data-md-component="sidebar" data-md-type="toc" >
<div class="md-sidebar__scrollwrap">
<div class="md-sidebar__inner">
<nav class="md-nav md-nav--secondary" aria-label="Table of contents">
<label class="md-nav__title" for="__toc">
<span class="md-nav__icon md-icon"></span>
Table of contents
</label>
<ul class="md-nav__list" data-md-component="toc" data-md-scrollfix>
<li class="md-nav__item">
<a href="#features" class="md-nav__link">
<span class="md-ellipsis">
Features
</span>
</a>
</li>
<li class="md-nav__item">
<a href="#non-features" class="md-nav__link">
<span class="md-ellipsis">
Non-features
</span>
</a>
</li>
<li class="md-nav__item">
<a href="#how-it-works" class="md-nav__link">
<span class="md-ellipsis">
How it works
</span>
</a>
<nav class="md-nav" aria-label="How it works">
<ul class="md-nav__list">
<li class="md-nav__item">
<a href="#visualization" class="md-nav__link">
<span class="md-ellipsis">
Visualization
</span>
</a>
</li>
</ul>
</nav>
</li>
</ul>
</nav>
</div>
</div>
</div>
<div class="md-content" data-md-component="content">
<article class="md-content__inner md-typeset">
<a href="https://github.com/trapexit/mergerfs/tree/master/mkdocs/docs/index.md" title="Edit this page" class="md-content__button md-icon">
<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 24 24"><path d="M10 20H6V4h7v5h5v3.1l2-2V8l-6-6H6c-1.1 0-2 .9-2 2v16c0 1.1.9 2 2 2h4zm10.2-7c.1 0 .3.1.4.2l1.3 1.3c.2.2.2.6 0 .8l-1 1-2.1-2.1 1-1c.1-.1.2-.2.4-.2m0 3.9L14.1 23H12v-2.1l6.1-6.1z"/></svg>
</a>
<a href="https://github.com/trapexit/mergerfs/tree/master/mkdocs/docs/index.md" title="View source of this page" class="md-content__button md-icon">
<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 24 24"><path d="M17 18c.56 0 1 .44 1 1s-.44 1-1 1-1-.44-1-1 .44-1 1-1m0-3c-2.73 0-5.06 1.66-6 4 .94 2.34 3.27 4 6 4s5.06-1.66 6-4c-.94-2.34-3.27-4-6-4m0 6.5a2.5 2.5 0 0 1-2.5-2.5 2.5 2.5 0 0 1 2.5-2.5 2.5 2.5 0 0 1 2.5 2.5 2.5 2.5 0 0 1-2.5 2.5M9.27 20H6V4h7v5h5v4.07c.7.08 1.36.25 2 .49V8l-6-6H6a2 2 0 0 0-2 2v16a2 2 0 0 0 2 2h4.5a8.2 8.2 0 0 1-1.23-2"/></svg>
</a>
<h1 id="mergerfs-a-featureful-union-filesystem">mergerfs - a featureful union filesystem</h1>
<p><strong>mergerfs</strong> is a
<a href="https://en.wikipedia.org/wiki/Filesystem_in_Userspace">FUSE</a> based
<a href="https://en.wikipedia.org/wiki/Union_mount">union filesystem</a> geared
towards simplifying storage and management of files across numerous
commodity storage devices. It is similar to <strong>mhddfs</strong>, <strong>unionfs</strong>,
and <strong>aufs</strong>.</p>
<h2 id="features">Features</h2>
<ul>
<li>Logicially combine numerous filesystems/paths into a single
mount point</li>
<li>Combine paths of the same or different filesystems</li>
<li>Ability to add or remove filesystems/paths without impacting the
rest of the data</li>
<li>Unaffected by individual filesystem failure</li>
<li>Configurable file selection and creation placement</li>
<li>Works with filesystems of any size</li>
<li>Works with filesystems of almost any type</li>
<li>Ignore read-only filesystems when creating files</li>
<li>Hard link copy-on-write / CoW</li>
<li>Runtime configurable</li>
<li>Support for extended attributes (xattrs)</li>
<li>Support for file attributes (chattr)</li>
<li>Support for POSIX ACLs</li>
</ul>
<h2 id="non-features">Non-features</h2>
<ul>
<li>Read/write overlay on top of readonly filesystem like OverlayFS</li>
<li>File whiteout</li>
<li>RAID like parity calculation</li>
<li>Redundency</li>
<li>Splitting of files across branches</li>
</ul>
<h2 id="how-it-works">How it works</h2>
<p>mergerfs logically merges multiple filesystem paths together. It acts
as a proxy to the underlying filesystem paths. Combining the
behaviors of some functions and being a selector for others.</p>
<p>When the contents of a directory are requested mergerfs combines the
list of files from each directory, deduplicating entries, and returns
that list.</p>
<p>When a file or directory is created a policy is first run to determine
which branch will be selected for the creation.</p>
<p>For functions which chant attributes or remove the file the behavior
may be applied to all instances found.</p>
<p>Read more about <a href="config/functions_categories_and_policies/">policies here</a>.</p>
<h3 id="visualization">Visualization</h3>
<div class="language-text highlight"><pre><span></span><code><span id="__span-0-1"><a id="__codelineno-0-1" name="__codelineno-0-1" href="#__codelineno-0-1"></a>A + B = C
</span><span id="__span-0-2"><a id="__codelineno-0-2" name="__codelineno-0-2" href="#__codelineno-0-2"></a>/disk1 /disk2 /merged
</span><span id="__span-0-3"><a id="__codelineno-0-3" name="__codelineno-0-3" href="#__codelineno-0-3"></a>| | |
</span><span id="__span-0-4"><a id="__codelineno-0-4" name="__codelineno-0-4" href="#__codelineno-0-4"></a>+-- /dir1 +-- /dir1 +-- /dir1
</span><span id="__span-0-5"><a id="__codelineno-0-5" name="__codelineno-0-5" href="#__codelineno-0-5"></a>| | | | | |
</span><span id="__span-0-6"><a id="__codelineno-0-6" name="__codelineno-0-6" href="#__codelineno-0-6"></a>| +-- file1 | +-- file2 | +-- file1
</span><span id="__span-0-7"><a id="__codelineno-0-7" name="__codelineno-0-7" href="#__codelineno-0-7"></a>| | +-- file3 | +-- file2
</span><span id="__span-0-8"><a id="__codelineno-0-8" name="__codelineno-0-8" href="#__codelineno-0-8"></a>+-- /dir2 | | +-- file3
</span><span id="__span-0-9"><a id="__codelineno-0-9" name="__codelineno-0-9" href="#__codelineno-0-9"></a>| | +-- /dir3 |
</span><span id="__span-0-10"><a id="__codelineno-0-10" name="__codelineno-0-10" href="#__codelineno-0-10"></a>| +-- file4 | +-- /dir2
</span><span id="__span-0-11"><a id="__codelineno-0-11" name="__codelineno-0-11" href="#__codelineno-0-11"></a>| +-- file5 | |
</span><span id="__span-0-12"><a id="__codelineno-0-12" name="__codelineno-0-12" href="#__codelineno-0-12"></a>+-- file6 | +-- file4
</span><span id="__span-0-13"><a id="__codelineno-0-13" name="__codelineno-0-13" href="#__codelineno-0-13"></a> |
</span><span id="__span-0-14"><a id="__codelineno-0-14" name="__codelineno-0-14" href="#__codelineno-0-14"></a> +-- /dir3
</span><span id="__span-0-15"><a id="__codelineno-0-15" name="__codelineno-0-15" href="#__codelineno-0-15"></a> | |
</span><span id="__span-0-16"><a id="__codelineno-0-16" name="__codelineno-0-16" href="#__codelineno-0-16"></a> | +-- file5
</span><span id="__span-0-17"><a id="__codelineno-0-17" name="__codelineno-0-17" href="#__codelineno-0-17"></a> |
</span><span id="__span-0-18"><a id="__codelineno-0-18" name="__codelineno-0-18" href="#__codelineno-0-18"></a> +-- file6
</span></code></pre></div>
</article>
</div>
<script>var target=document.getElementById(location.hash.slice(1));target&&target.name&&(target.checked=target.name.startsWith("__tabbed_"))</script>
</div>
<button type="button" class="md-top md-icon" data-md-component="top" hidden>
<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 24 24"><path d="M13 20h-2V8l-5.5 5.5-1.42-1.42L12 4.16l7.92 7.92-1.42 1.42L13 8z"/></svg>
Back to top
</button>
</main>
<footer class="md-footer">
<nav class="md-footer__inner md-grid" aria-label="Footer" >
<a href="quickstart/" class="md-footer__link md-footer__link--next" aria-label="Next: QuickStart">
<div class="md-footer__title">
<span class="md-footer__direction">
Next
</span>
<div class="md-ellipsis">
QuickStart
</div>
</div>
<div class="md-footer__button md-icon">
<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 24 24"><path d="M4 11v2h12l-5.5 5.5 1.42 1.42L19.84 12l-7.92-7.92L10.5 5.5 16 11z"/></svg>
</div>
</a>
</nav>
<div class="md-footer-meta md-typeset">
<div class="md-footer-meta__inner md-grid">
<div class="md-copyright">
Made with
<a href="https://squidfunk.github.io/mkdocs-material/" target="_blank" rel="noopener">
Material for MkDocs
</a>
</div>
</div>
</div>
</footer>
</div>
<div class="md-dialog" data-md-component="dialog">
<div class="md-dialog__inner md-typeset"></div>
</div>
<script id="__config" type="application/json">{"base": ".", "features": ["content.action.edit", "content.action.view", "content.code.copy", "content.code.select", "navigation.footer", "navigation.instant", "navigation.instant.prefetch", "navigation.path", "navigation.top", "navigation.tracking", "optimize", "search.share", "toc.follow"], "search": "assets/javascripts/workers/search.6ce7567c.min.js", "translations": {"clipboard.copied": "Copied to clipboard", "clipboard.copy": "Copy to clipboard", "search.result.more.one": "1 more on this page", "search.result.more.other": "# more on this page", "search.result.none": "No matching documents", "search.result.one": "1 matching document", "search.result.other": "# matching documents", "search.result.placeholder": "Type to start searching", "search.result.term.missing": "Missing", "select.version": "Select version"}}</script>
<script src="assets/javascripts/bundle.88dd0f4e.min.js"></script>
</body>
</html>