In the Windows API (with some exceptions discussed in the following paragraphs), the maximum length for a path is MAX_PATH , which is defined as 260 characters.
Does the Duplicati overcome that limitation as some other software like Total Commander and also backups/restores folders/files that have path more than 260 characters on Windows systems?
The reason why I am asking is that I have some folders/files that exceed that limit and I am interesting if they will be properly backedup/restored.
I had hoped for a pure “yes” but got a conditional one from the latest Duplicati canary and latest Windows 10. The test was to use UNC syntax in a command prompt to make folders at C:\ with 100 character folder names:
C:\>mkdir \\?\C:\1234567890 ... and not quibbling over off-by-1-or-whatever, just trying to get long by repeating this to 4 levels. At each level I use echo redirect to leave a text file with a meaningful name. Repeat.
Edit of an existing backup job wasn’t able to see the deep files, however selecting a not-so-deep level did get backup all the way down, and restore did show the deep levels, and restored the deep file to its original place.
Support long filenames on Windows #320 from 2014 is what made me hope that this was all set. Not perfectly but definitely an objective. I think a UNC bug was found and fixed sometime in late 2016. Now on to late news.
C:\Program Files\Duplicati 2>duplicati.commandline.exe help usn-policy
--usn-policy (Enumeration): Controls the use of NTFS Update Sequence Numbers
This setting controls the usage of NTFS USN numbers, which allows
Duplicati to obtain a list of files and folders much faster. If this is
set to "off", Duplicati will not attempt to use USN. Setting this to
"auto" makes Duplicati attempt to use USN, and fail silently if that was
not allowed or supported. A setting of "on" will also make Duplicati
attempt to use USN, but will produce a warning message in the log if it
fails. Setting it to "required" will make Duplicati abort the backup if
the USN usage fails. This feature is only supported on Windows and
requires administrative privileges.
* values: Auto, On, Off, Required
* default value: off
C:\Program Files\Duplicati 2>
also seems to imply that it won’t affect your operation unless you turn it on. A fix for it also appears underway.
So the answer to your question seems to be generally yes unless you are unable to specify even the starting point without going too deep. Maybe the answer will also vary if you use an old Windows version. Please test.
As further evidence that things generally work, some people back up C:\ and that can deliver very long paths.