Remember that the default policy for `getattr` is `ff`. The information for the first directory found will be returned. If it wasn't the directory which had been updated then it will appear outdated.
@ -874,30 +878,13 @@ Be sure to use the following options:
Be sure to set `cache.files=partial|full|auto-full` or turn off `direct_io`. rtorrent and some other applications use [mmap](http://linux.die.net/man/2/mmap) to read and write to files and offer no fallback to traditional methods. FUSE does not currently support mmap while using `direct_io`. There may be a performance penalty on writes with `direct_io` off as well as the problem of double caching but it's the only way to get such applications to work. If the performance loss is too high for other apps you can mount mergerfs twice. Once with `direct_io` enabled and one without it. Be sure to set `dropcacheonclose=true` if not using `direct_io`.
#### rtorrent fails with files >= 4GiB
This is a kernel bug with mmap and FUSE on 32bit platforms. A fix should become available for all LTS releases.
There appears to be a bug in the OpenVZ kernel with regard to how it handles ioctl calls. It is making invalid requests which leads to a crash. As of 2019-12-10 there is a bug report filed with OpenVZ but it is not yet fixed.
#### Plex doesn't work with mergerfs
It does. If you're trying to put Plex's config / metadata / database on mergerfs you can't set `cache.fles=off` because Plex is using sqlite3 with mmap enabled. Shared mmap is not supported by Linux's FUSE implementation when page caching is disabled. To fix this place the data elsewhere (preferable) or enable `cache.files` (with `dropcacheonclose=true`). Sqlite3 does not need mmap but the developer needs to fall back to standard IO if mmap fails.
It does. If you're trying to put Plex's config / metadata / database on mergerfs you can't set `cache.files=off` because Plex is using sqlite3 with mmap enabled. Shared mmap is not supported by Linux's FUSE implementation when page caching is disabled. To fix this place the data elsewhere (preferable) or enable `cache.files` (with `dropcacheonclose=true`). Sqlite3 does not need mmap but the developer needs to fall back to standard IO if mmap fails.
If the issue is that scanning doesn't seem to pick up media then be sure to set `func.getattr=newest` though generally a full scan will pick up all media anyway.
#### mmap performance is really bad
There [is/was a bug](https://lkml.org/lkml/2016/3/16/260) in caching which affects overall performance of mmap through FUSE in Linux 4.x kernels. It is fixed in [4.4.10 and 4.5.4](https://lkml.org/lkml/2016/5/11/59).
#### When a program tries to move or rename a file it fails
Please read the section above regarding [rename & link](#rename--link).
@ -957,48 +944,6 @@ First upgrade if possible, check the known bugs section, and contact trapexit.
There seems to be an issue with Linux version `4.9.0` and above in which an invalid message appears to be transmitted to libfuse (used by mergerfs) causing it to exit. No messages will be printed in any logs as it's not a proper crash. Debugging of the issue is still ongoing and can be followed via the [fuse-devel thread](https://sourceforge.net/p/fuse/mailman/message/35662577).
#### mergerfs under heavy load and memory pressure leads to kernel panic
https://lkml.org/lkml/2016/9/14/527
```
[25192.515454] kernel BUG at /build/linux-a2WvEb/linux-4.4.0/mm/workingset.c:346!
There is a bug in the kernel. A work around appears to be turning off `splice`. Don't add the `splice_*` arguments or add `no_splice_write,no_splice_move,no_splice_read`. This, however, is not guaranteed to work.
#### rm: fts_read failed: No such file or directory
@ -1011,7 +956,7 @@ Please update. This is only happened to mergerfs versions at or below v2.25.x an
Users have reported running mergerfs on everything from a Raspberry Pi to dual socket Xeon systems with >20 cores. I'm aware of at least a few companies which use mergerfs in production. [Open Media Vault](https://www.openmediavault.org) includes mergerfs as its sole solution for pooling drives. The author of mergerfs had it running for over 300 days managing 16+ drives with reasonably heavy 24/7 read and write usage. Stopping only after the machine's power supply died.
Most serious issues (crashes or data corruption) have been due to kernel bugs. All of which are fixed in stable releases.
Most serious issues (crashes or data corruption) have been due to [kernel bugs](https://github.com/trapexit/mergerfs/wiki/Kernel-Issues-&-Bugs). All of which are fixed in stable releases.
#### Can mergerfs be used with drives which already have data / are in use?
Antonio SJ Musumeci
4 years ago