What is "sync.ffs_lock" file?

[sun12758]

Hello.
I am new user.
Everytime I try to mirror myfiles, it indicates, looking for "sync.ffs_lock" for 16 sec.
Is it okay to delete it before I use mirroring?
(from source and target ? )

Thank you !!

[xCSxXenon]

It is created so two different syncs don't edit data at the same time. You can delete them, be sure that there are no active syncs going