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<h1 id="general-information-and-overview">General Information and Overview</h1>
<h2 id="how-well-does-mergerfs-scale-is-it-production-ready">How well does mergerfs scale? Is it "production ready?"</h2>
<p>Users have reported running mergerfs on everything from a Raspberry Pi
to dual socket Xeon systems with &gt;20 cores. I'm aware of at least a
few companies which use mergerfs in production. <a href="https://www.openmediavault.org">Open Media
Vault</a> includes mergerfs as its sole
solution for pooling filesystems. The author of mergerfs had it
running for over 300 days managing 16+ devices with reasonably heavy
24/7 read and write usage. Stopping only after the machine's power
supply died.</p>
<p>Most serious issues (crashes or data corruption) have been due to
<a href="https://github.com/trapexit/mergerfs/wiki/Kernel-Issues-&amp;-Bugs">kernel
bugs</a>. All
of which are fixed in stable releases.</p>
<h2 id="why-use-fuse-why-not-a-kernel-based-solution">Why use FUSE? Why not a kernel based solution?</h2>
<p>As with any solution to a problem, there are advantages and
disadvantages to each one.</p>
<p>A FUSE based solution has all the downsides of FUSE:</p>
<ul>
<li>Higher IO latency due to the trips in and out of kernel space</li>
<li>Higher general overhead due to trips in and out of kernel space</li>
<li>Double caching when using page caching</li>
<li>Misc limitations due to FUSE's design</li>
</ul>
<p>But FUSE also has a lot of upsides:</p>
<ul>
<li>Easier to offer a cross platform solution</li>
<li>Easier forward and backward compatibility</li>
<li>Easier updates for users</li>
<li>Easier and faster release cadence</li>
<li>Allows more flexibility in design and features</li>
<li>Overall easier to write, secure, and maintain</li>
<li>Much lower barrier to entry (getting code into the kernel takes a
  lot of time and effort initially)</li>
</ul>
<p>FUSE was chosen because of all the advantages listed above. The
negatives of FUSE do not outweigh the positives.</p>
<h2 id="is-my-oss-libfuse-needed-for-mergerfs-to-work">Is my OS's libfuse needed for mergerfs to work?</h2>
<p>No. Normally <code>mount.fuse</code> is needed to get mergerfs (or any FUSE
filesystem to mount using the <code>mount</code> command but in vendoring the
libfuse library the <code>mount.fuse</code> app has been renamed to
<code>mount.mergerfs</code> meaning the filesystem type in <code>fstab</code> can simply be
<code>mergerfs</code>. That said there should be no harm in having it installed
and continuing to using <code>fuse.mergerfs</code> as the type in <code>/etc/fstab</code>.</p>
<p>If <code>mergerfs</code> doesn't work as a type it could be due to how the
<code>mount.mergerfs</code> tool was installed. Must be in <code>/sbin/</code> with proper
permissions.</p>
<h2 id="why-was-splice-support-removed">Why was splice support removed?</h2>
<p>After a lot of testing over the years, splicing always appeared to
at best, provide equivalent performance, and in some cases, worse
performance. Splice is not supported on other platforms forcing a
traditional read/write fallback to be provided. The splice code was
removed to simplify the codebase.</p>


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