note that mergerfs should be run as root

README.md

@@ -306,6 +306,7 @@ A B C
 
 # TIPS / NOTES
 
+* Run mergerfs as `root` unless you're merging paths which are owned by the same user otherwise strange permission issues may arise.
 * https://github.com/trapexit/backup-and-recovery-howtos : A set of guides / howtos on creating a data storage system, backing it up, maintaining it, and recovering from failure.
 * If you don't see some directories / files you expect in a merged point be sure the user has permission to all the underlying directories. If `/drive0/a` has is owned by `root:root` with ACLs set to `0700` and `/drive1/a` is `root:root` and `0755` you'll see only `/drive1/a`. Use `mergerfs.fsck` to audit the drive for out of sync permissions.
 * Do *not* use `direct_io` if you expect applications (such as rtorrent) to [mmap](http://linux.die.net/man/2/mmap) files. It is not currently supported in FUSE w/ `direct_io` enabled.

man/mergerfs.1

@@ -685,6 +685,9 @@ https://github.com/trapexit/scorch
 scorch: A tool to help discover silent corruption of files
 .SH TIPS / NOTES
 .IP \[bu] 2
+Run mergerfs as \f[C]root\f[] unless you\[aq]re merging paths which are
+owned by the same user otherwise strange permission issues may arise.
+.IP \[bu] 2
 https://github.com/trapexit/backup\-and\-recovery\-howtos : A set of
 guides / howtos on creating a data storage system, backing it up,
 maintaining it, and recovering from failure.