|
|
|
@ -1,14 +1,41 @@ |
|
|
|
# mergerfs - a featureful union filesystem |
|
|
|
|
|
|
|
**mergerfs** is a |
|
|
|
[FUSE](https://en.wikipedia.org/wiki/Filesystem_in_Userspace) based |
|
|
|
[union filesystem](https://en.wikipedia.org/wiki/Union_mount) geared |
|
|
|
towards simplifying storage and management of files across numerous |
|
|
|
commodity storage devices. It is similar to [**mhddfs**, **unionfs**, |
|
|
|
**aufs**, **DrivePool**, etc.](project_comparisons.md) Allowing for |
|
|
|
the aggregation of storage without the more rigid requirements and |
|
|
|
failure conditions of [RAID and other |
|
|
|
technologies](project_comparisons.md). |
|
|
|
**mergerfs** is a [union |
|
|
|
filesystem](https://en.wikipedia.org/wiki/Union_mount) that makes |
|
|
|
multiple storage devices or filesystems appear as a single unified |
|
|
|
directory. Built on [FUSE (Filesystem in |
|
|
|
Userspace)](https://en.wikipedia.org/wiki/Filesystem_in_Userspace), it |
|
|
|
is designed to simplify how you manage files across several |
|
|
|
independent filesystems without the complexity, fragility, or cost of |
|
|
|
RAID or similar storage aggregation technologies. |
|
|
|
|
|
|
|
Think of mergerfs as a smart pooling layer: you can combine any number |
|
|
|
of [existing |
|
|
|
filesystems](faq/usage_and_functionality.md#can-mergerfs-be-used-with-filesystems-which-already-have-data) |
|
|
|
— whether they are on hard drives, SSDs, network shares, or other |
|
|
|
mounted storage — into what looks like one large filesystem, while |
|
|
|
still maintaining direct access to each individual filesystem. Unlike |
|
|
|
RAID, there's no rebuild process if a device fails. You only lose the |
|
|
|
files that were on that specific filesystem. You can also add or |
|
|
|
remove filesystems at any time without restructuring your entire pool. |
|
|
|
|
|
|
|
mergerfs excels at cost-effective storage expansion, making it ideal |
|
|
|
for media libraries, backups, archival data, and other write-sometimes, |
|
|
|
read-often workloads where you need lots of space but don't want |
|
|
|
the overhead of traditional storage technologies. |
|
|
|
|
|
|
|
**Key advantages:** |
|
|
|
|
|
|
|
* Mix and match filesystems of any size, type, or underlying device |
|
|
|
* No parity calculations or rebuild times |
|
|
|
* Add or remove filesystems on the fly |
|
|
|
* Direct access to files on individual filesystems when needed |
|
|
|
* Flexible policies for controlling where new files are created |
|
|
|
|
|
|
|
For users seeking alternatives to mhddfs, unionfs, aufs, or DrivePool, |
|
|
|
mergerfs offers a mature, actively maintained solution with extensive |
|
|
|
configuration options and documentation. See the [project comparisons |
|
|
|
for more comparisons.](project_comparisons.md) |
|
|
|
|
|
|
|
|
|
|
|
## Features |
|
|
|
@ -19,7 +46,7 @@ technologies](project_comparisons.md). |
|
|
|
* Ability to add or remove filesystems/paths without impacting the |
|
|
|
rest of the data |
|
|
|
* Unaffected by individual filesystem failure |
|
|
|
* Configurable file selection and creation placement |
|
|
|
* Configurable file creation placement |
|
|
|
* File IO [passthrough](config/passthrough.md) for near native IO |
|
|
|
performance (where supported) |
|
|
|
* Works with filesystems of any size |
|
|
|
@ -28,7 +55,7 @@ technologies](project_comparisons.md). |
|
|
|
* Ignore read-only filesystems when creating files |
|
|
|
* [Hard links](faq/technical_behavior_and_limitations.md#do-hard-links-work) |
|
|
|
* Hard link [copy-on-write / CoW](config/link-cow.md) |
|
|
|
* [Runtime configurable](runtime_interface.md) |
|
|
|
* [Runtime configurability](runtime_interface.md) |
|
|
|
* Support for extended attributes (xattrs) |
|
|
|
* Support for file attributes (chattr) |
|
|
|
* Support for POSIX ACLs |
|
|
|
@ -36,12 +63,14 @@ technologies](project_comparisons.md). |
|
|
|
|
|
|
|
## Non-features |
|
|
|
|
|
|
|
* Read/write overlay on top of read-only filesystem like OverlayFS |
|
|
|
* File whiteout |
|
|
|
* RAID like redundancy (see [SnapRAID](https://www.snapraid.it) and |
|
|
|
[NonRAID](https://github.com/qvr/nonraid)) |
|
|
|
* Redundancy |
|
|
|
* LVM/RAID style block device aggregation |
|
|
|
* Data integrity checks, snapshots, file versioning |
|
|
|
* Read/write overlays on top of read-only filesystems (like OverlayFS) |
|
|
|
* File whiteout |
|
|
|
* Splitting of files across branches |
|
|
|
* Active rebalancing of content |
|
|
|
|
|
|
|
|
|
|
|
## How it works |
|
|
|
@ -62,7 +91,7 @@ For functions which change attributes or remove the file the behavior |
|
|
|
may be applied to all instances found. |
|
|
|
|
|
|
|
The way in which mergerfs behaves is controlled by the |
|
|
|
[config/options/settings](config/options.md). More specifically by |
|
|
|
[config / options / settings](config/options.md). More specifically by |
|
|
|
[policies](config/functions_categories_policies.md). |
|
|
|
|
|
|
|
|
|
|
|
@ -90,7 +119,6 @@ A + B = C |
|
|
|
+-- file7 +-- file7 +-- file7 |
|
|
|
``` |
|
|
|
|
|
|
|
|
|
|
|
## Getting Started |
|
|
|
|
|
|
|
Head to the [quick start guide](quickstart.md). |
|
|
|
@ -107,3 +135,6 @@ Head to the [quick start guide](quickstart.md). |
|
|
|
like something is not explained sufficiently or missing please [ask |
|
|
|
in one of the supported forums](support.md#contact-issue-submission) |
|
|
|
and the docs will be updated. |
|
|
|
* The search feature of MkDocs is not great. Searching for "literal |
|
|
|
strings" will generally not work. Alernative solutions are being |
|
|
|
investigated. |
trapexit
5 days ago
GitHub