Ordinarily, you should unmount user-defined file systems (UDFS) before save and restore operations. Menu options 21, 22, and 23 of the GO SAVE command provide an option to unmount UDFSs prior to the save.
CPD3788 - File system information not saved for <your udfs>
The server does not save objects that are contained in a directory over which you mount a UDFS. For example, if directory /appl has objects in it and if you mount a UDFS over /appl, the server does not save the objects in /appl. The server only saves the objects in the UDFS.
You may mount your UDFS as read-only. Because the server does not save any file system information for a mounted UDFS, the server does not save the read-only attribute. Therefore, the server restores the objects from the UDFS without the read-only attribute.
If the mounted UDFS is read-only and you specify UPDHST(*YES), the server issues message CPI3726 that indicates that the server did not update the save history for objects.
SAV OBJ(('/appl/dir1')
Where the server mounted the UDFS over directory /appl/dir1.