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@ -670,7 +670,7 @@ writable. |
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Even though it's a more niche situation this hack breaks normal |
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security and behavior and as such is `off` by default. If set to `git` |
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it will only perform the hack when the path in question includes |
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`/.git/`. `all` will result it applying anytime a readonly file which |
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`/.git/`. `all` will result it applying anytime a read-only file which |
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is empty is opened for writing. |
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@ -2089,15 +2089,16 @@ first directory will be placed on the same branch because it is |
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preserving paths. |
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This catches a lot of new users off guard but changing the default |
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would break the setup for many existing users. If you do not care |
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about path preservation and wish your files to be spread across all |
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your filesystems change to `mfs` or similar policy as described |
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|
above. If you do want path preservation you'll need to perform the |
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|
manual act of creating paths on the filesystems you want the data to |
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land on before transferring your data. Setting `func.mkdir=epall` can |
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|
simplify managing path preservation for `create`. Or use |
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`func.mkdir=rand` if you're interested in just grouping together |
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|
directory content by filesystem. |
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would break the setup for many existing users and this policy is the |
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|
safest policy as it will not change the general layout of the existing |
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|
filesystems. If you do not care about path preservation and wish your |
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|
files to be spread across all your filesystems change to `mfs` or |
|
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|
similar policy as described above. If you do want path preservation |
|
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|
you'll need to perform the manual act of creating paths on the |
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|
filesystems you want the data to land on before transferring your |
|
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|
data. Setting `func.mkdir=epall` can simplify managing path |
|
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|
preservation for `create`. Or use `func.mkdir=rand` if you're |
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|
interested in just grouping together directory content by filesystem. |
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#### Do hardlinks work? |
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@ -2119,6 +2120,16 @@ mergerfs pool that includes all the paths you need if you want links |
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to work. |
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#### Does FICLONE or FICLONERANGE work? |
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Unfortunately not. FUSE, the technology mergerfs is based on, does not |
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|
support the `clone_file_range` feature needed for it to work. mergerfs |
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|
won't even know such a request is made. The kernel will simply return |
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|
an error back to the application making the request. |
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Should FUSE gain the ability mergerfs will be updated to support it. |
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#### Can I use mergerfs without SnapRAID? SnapRAID without mergerfs? |
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Yes. They are completely unrelated pieces of software. |
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@ -2237,103 +2248,6 @@ traditional read/write fallback to be provided. The splice code was |
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removed to simplify the codebase. |
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#### Why use mergerfs over mhddfs? |
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|
mhddfs is no longer maintained and has some known stability and |
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|
security issues (see below). mergerfs provides a superset of mhddfs' |
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|
features and should offer the same or maybe better performance. |
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|
Below is an example of mhddfs and mergerfs setup to work similarly. |
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`mhddfs -o mlimit=4G,allow_other /mnt/drive1,/mnt/drive2 /mnt/pool` |
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`mergerfs -o minfreespace=4G,category.create=ff /mnt/drive1:/mnt/drive2 /mnt/pool` |
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#### Why use mergerfs over aufs? |
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|
aufs is mostly abandoned and no longer available in many distros. |
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|
While aufs can offer better peak performance mergerfs provides more |
|
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|
configurability and is generally easier to use. mergerfs however does |
|
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|
not offer the overlay / copy-on-write (CoW) features which aufs and |
|
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|
overlayfs have. |
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|
#### Why use mergerfs over unionfs? |
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|
UnionFS is more like aufs than mergerfs in that it offers overlay / |
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|
CoW features. If you're just looking to create a union of filesystems |
|
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|
and want flexibility in file/directory placement then mergerfs offers |
|
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|
that whereas unionfs is more for overlaying RW filesystems over RO |
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|
ones. |
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|
#### Why use mergerfs over overlayfs? |
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|
Same reasons as with unionfs. |
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|
#### Why use mergerfs over LVM/ZFS/BTRFS/RAID0 drive concatenation / striping? |
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|
With simple JBOD / drive concatenation / stripping / RAID0 a single |
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|
drive failure will result in full pool failure. mergerfs performs a |
|
|
|
similar function without the possibility of catastrophic failure and |
|
|
|
the difficulties in recovery. Drives may fail, however, all other data |
|
|
|
will continue to be accessible. |
|
|
|
|
|
|
|
When combined with something like [SnapRaid](http://www.snapraid.it) |
|
|
|
and/or an offsite backup solution you can have the flexibility of JBOD |
|
|
|
without the single point of failure. |
|
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|
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|
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|
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|
|
#### Why use mergerfs over ZFS? |
|
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|
mergerfs is not intended to be a replacement for ZFS. mergerfs is |
|
|
|
intended to provide flexible pooling of arbitrary filesystems (local |
|
|
|
or remote), of arbitrary sizes, and arbitrary filesystems. For `write |
|
|
|
once, read many` usecases such as bulk media storage. Where data |
|
|
|
integrity and backup is managed in other ways. In that situation ZFS |
|
|
|
can introduce a number of costs and limitations as described |
|
|
|
[here](http://louwrentius.com/the-hidden-cost-of-using-zfs-for-your-home-nas.html), |
|
|
|
[here](https://markmcb.com/2020/01/07/five-years-of-btrfs/), and |
|
|
|
[here](https://utcc.utoronto.ca/~cks/space/blog/solaris/ZFSWhyNoRealReshaping). |
|
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|
|
|
|
|
|
|
|
#### Why use mergerfs over UnRAID? |
|
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|
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|
UnRAID is a full OS and its storage layer, as I understand, is |
|
|
|
proprietary and closed source. Users who have experience with both |
|
|
|
have said they prefer the flexibility offered by mergerfs and for some |
|
|
|
the fact it is free and open source is important. |
|
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|
There are a number of UnRAID users who use mergerfs as well though I'm |
|
|
|
not entirely familiar with the use case. |
|
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|
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|
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|
|
|
|
#### Why use mergerfs over StableBit's DrivePool? |
|
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|
|
|
DrivePool works only on Windows so not as common an alternative as |
|
|
|
other Linux solutions. If you want to use Windows then DrivePool is a |
|
|
|
good option. Functionally the two projects work a bit |
|
|
|
differently. DrivePool always writes to the filesystem with the most |
|
|
|
free space and later rebalances. mergerfs does not offer rebalance but |
|
|
|
chooses a branch at file/directory create time. DrivePool's |
|
|
|
rebalancing can be done differently in any directory and has file |
|
|
|
pattern matching to further customize the behavior. mergerfs, not |
|
|
|
having rebalancing does not have these features, but similar features |
|
|
|
are planned for mergerfs v3. DrivePool has builtin file duplication |
|
|
|
which mergerfs does not natively support (but can be done via an |
|
|
|
external script.) |
|
|
|
|
|
|
|
There are a lot of misc differences between the two projects but most |
|
|
|
features in DrivePool can be replicated with external tools in |
|
|
|
combination with mergerfs. |
|
|
|
|
|
|
|
Additionally DrivePool is a closed source commercial product vs |
|
|
|
mergerfs a ISC licensed OSS project. |
|
|
|
|
|
|
|
|
|
|
|
#### What should mergerfs NOT be used for? |
|
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|
|
|
* databases: Even if the database stored data in separate files |
|
|
|
@ -2485,6 +2399,114 @@ used so threads trying to change credentials don't starve. This isn't |
|
|
|
the best solution but should work reasonably well assuming there are |
|
|
|
few users. |
|
|
|
|
|
|
|
# mergerfs versus X |
|
|
|
|
|
|
|
#### mhddfs |
|
|
|
|
|
|
|
mhddfs had not been maintained for some time and has some known |
|
|
|
stability and security issues. mergerfs provides a superset of mhddfs' |
|
|
|
features and should offer the same or better performance. |
|
|
|
|
|
|
|
Below is an example of mhddfs and mergerfs setup to work similarly. |
|
|
|
|
|
|
|
`mhddfs -o mlimit=4G,allow_other /mnt/drive1,/mnt/drive2 /mnt/pool` |
|
|
|
|
|
|
|
`mergerfs -o minfreespace=4G,category.create=ff /mnt/drive1:/mnt/drive2 /mnt/pool` |
|
|
|
|
|
|
|
|
|
|
|
#### aufs |
|
|
|
|
|
|
|
aufs is mostly abandoned and no longer available in most Linux distros. |
|
|
|
|
|
|
|
While aufs can offer better peak performance mergerfs provides more |
|
|
|
configurability and is generally easier to use. mergerfs however does |
|
|
|
not offer the overlay / copy-on-write (CoW) features which aufs has. |
|
|
|
|
|
|
|
|
|
|
|
#### unionfs-fuse |
|
|
|
|
|
|
|
unionfs-fuse is more like aufs than mergerfs in that it offers overlay / |
|
|
|
copy-on-write (CoW) features. If you're just looking to create a union |
|
|
|
of filesystems and want flexibility in file/directory placement then |
|
|
|
mergerfs offers that whereas unionfs is more for overlaying read/write |
|
|
|
filesystems over read-only ones. |
|
|
|
|
|
|
|
|
|
|
|
#### overlayfs |
|
|
|
|
|
|
|
overlayfs is similar to aufs and unionfs-fuse in that it also is |
|
|
|
primarily used to layer a read/write filesystem over one or more |
|
|
|
read-only filesystems. It does not have the ability to spread |
|
|
|
files/directories across numerous filesystems. |
|
|
|
|
|
|
|
|
|
|
|
#### RAID0, JBOD, drive concatenation, striping |
|
|
|
|
|
|
|
With simple JBOD / drive concatenation / stripping / RAID0 a single |
|
|
|
drive failure will result in full pool failure. mergerfs performs a |
|
|
|
similar function without the possibility of catastrophic failure and |
|
|
|
the difficulties in recovery. Drives may fail but all other |
|
|
|
filesystems and their data will continue to be accessible. |
|
|
|
|
|
|
|
The main practical difference with mergerfs is the fact you don't |
|
|
|
actually have contiguous space as large as if you used those other |
|
|
|
technologies. Meaning you can't create a 2TB file on a pool of 2 1TB |
|
|
|
filesystems. |
|
|
|
|
|
|
|
When combined with something like [SnapRaid](http://www.snapraid.it) |
|
|
|
and/or an offsite backup solution you can have the flexibility of JBOD |
|
|
|
without the single point of failure. |
|
|
|
|
|
|
|
|
|
|
|
#### UnRAID |
|
|
|
|
|
|
|
UnRAID is a full OS and its storage layer, as I understand, is |
|
|
|
proprietary and closed source. Users who have experience with both |
|
|
|
have often said they prefer the flexibility offered by mergerfs and |
|
|
|
for some the fact it is open source is important. |
|
|
|
|
|
|
|
There are a number of UnRAID users who use mergerfs as well though I'm |
|
|
|
not entirely familiar with the use case. |
|
|
|
|
|
|
|
For semi-static data mergerfs + [SnapRaid](http://www.snapraid.it) |
|
|
|
provides a similar solution. |
|
|
|
|
|
|
|
|
|
|
|
#### ZFS |
|
|
|
|
|
|
|
mergerfs is very different from ZFS. mergerfs is intended to provide |
|
|
|
flexible pooling of arbitrary filesystems (local or remote), of |
|
|
|
arbitrary sizes, and arbitrary filesystems. For `write once, read |
|
|
|
many` usecases such as bulk media storage. Where data integrity and |
|
|
|
backup is managed in other ways. In those usecases ZFS can introduce a |
|
|
|
number of costs and limitations as described |
|
|
|
[here](http://louwrentius.com/the-hidden-cost-of-using-zfs-for-your-home-nas.html), |
|
|
|
[here](https://markmcb.com/2020/01/07/five-years-of-btrfs/), and |
|
|
|
[here](https://utcc.utoronto.ca/~cks/space/blog/solaris/ZFSWhyNoRealReshaping). |
|
|
|
|
|
|
|
|
|
|
|
#### StableBit's DrivePool |
|
|
|
|
|
|
|
DrivePool works only on Windows so not as common an alternative as |
|
|
|
other Linux solutions. If you want to use Windows then DrivePool is a |
|
|
|
good option. Functionally the two projects work a bit |
|
|
|
differently. DrivePool always writes to the filesystem with the most |
|
|
|
free space and later rebalances. mergerfs does not offer rebalance but |
|
|
|
chooses a branch at file/directory create time. DrivePool's |
|
|
|
rebalancing can be done differently in any directory and has file |
|
|
|
pattern matching to further customize the behavior. mergerfs, not |
|
|
|
having rebalancing does not have these features, but similar features |
|
|
|
are planned for mergerfs v3. DrivePool has builtin file duplication |
|
|
|
which mergerfs does not natively support (but can be done via an |
|
|
|
external script.) |
|
|
|
|
|
|
|
There are a lot of misc differences between the two projects but most |
|
|
|
features in DrivePool can be replicated with external tools in |
|
|
|
combination with mergerfs. |
|
|
|
|
|
|
|
Additionally DrivePool is a closed source commercial product vs |
|
|
|
mergerfs a ISC licensed OSS project. |
|
|
|
|
|
|
|
|
|
|
|
# SUPPORT |
|
|
|
|
|
|
|
|
trapexit
10 months ago
GitHub