Q: How are Symbolic Links managed by MergerFS on a server when copying files over SSHFS ?

[HaroPo]

Hi,
I am copying files from a client system (Linux Mint 21) to a NAS using 'Nemo' (v5.4.3) and SSHFS (v3.7.1 see details at the end of the message) between them.

SSHFS seems doing its job fine after I set UID+GID identical on both systems.

MergerFS runs on the NAS with the following mount options:

defaults,\
...
.create=epff\
.search=epall\
...

(more details to come when able to shutdown MergerFS: The mount script purposely in the mount point / directory is invisible right now)

Off of 4 SSDs, only one is receiving the files I am transferring today, as expected/wanted behaviour since only this SSD/"branch" has the existing path.

Amongst the files are some symbolic links (symlinks) and some are broken (on purpose: external drive Not mounted, etc...) on the source/client file system.

Now, I would like these links to remain unchanged (because I am doing backups...) and I get a warning message from 'Nemo' : "Cancel / Skip / Skip All"

Q: I wonder where (MergerFS, SSHFS, Nemo) is the problem happening ?

I tried to workaround things by copying existing directories on the client that are pointed to by some of these links, But, another "surprise":

"Input/Output error" But, the "symlink" has been created successfully on the NAS.

Then, the exact same copy scenario with another "symlink" gives me, this time, the following error message: "File system does Not support symbolic links"...

Huh !?!?!?

So, it's how I came here to ask more information about how "symlinks" are handled by MergerFS, while I am conscious that SSHFS and 'Nemo' could (must) have their part into this "little mess".

Thank you for reading me until there. :-)

Best regards,
HP_

About SSHFS:

SSHFS version 3.7.1
FUSE library version 3.10.5
using FUSE kernel interface version 7.31
fusermount3 version: 3.10.5

(edit: moving personal comment a line under the code section related to MergerFS mount options, else long text needs to scroll it right/left to read ...)

[trapexit]

There is nothing special about mergerfs + sshfs. symlinks are just another file type and work the same as any other filesystem mergerfs talks to. There is no special management.

BTW... there is no such thing as "copying": https://trapexit.github.io/mergerfs/faq/technical_behavior_and_limitations/#how-does-mergerfs-handle-moving-and-copying-of-files

For a symlink it is just created. There is nothing more or less to it.

It would help if you provided specific examples: https://trapexit.github.io/mergerfs/support/

Your problem is likely sshfs.