Backup network CIFS share to external storage

I am looking for a way to backup/sync the contents of a CIFS share to an external USB in Ubuntu, from the CLI. I have mounted the cifs share and also mounted the external storage USB.

I have the following directory structure on the CIFS share:

$ mount -t cifs -o username='<myusername>',password='<mypassword>' //<mycifs_ip_address>/<mycifs_share_name> /mnt/myshare
$ ls /mnt/myshare
BackupFiles > > 11_28_2014 > File_Today_11_16_2013.txt > File_Yesterday_07_02_2014.txt > 07_16_2015 > File_Yesterday_04_29_2015.txt > File_Tomorrow_10_12_2015.txt > File_Yesterday_07_02_2015.txt > 12_05_2016 > File_Tomorrow_06_10_2016.txt
abc.pdf
File_Names.csv
Test.txt

Note that 11_28_2014, 07_16_2015 and 12_05_2016 are directories.

I have the following directory structure on the external USB:

$ mount /dev/sha4 mnt/myusbback
$ ls /mnt/myusbback
BackupFiles > > 11_28_2014 > File_Today_11_16_2013.txt > File_Yesterday_07_02_2014.txt
def_config.sh
File_Output.dat
Testing_doc.docx

Additional information:

1. I am using Ubuntu Server 16.04.1
2. When mounting the CIFS share, I need to specify a username and password. The CIFS share has been set up to require these credentials when accessing it.

Problem:

I am looking for a way to:

1. sense the directory structure on the CIFS share and on the external USB and create missing directories on the USB
2. copy files from the CIFS share into appropriate folders on the USB, if they are missing from the USB
3. Sync the BackupFiles directory (including all its sub-directories) on the CIFS share and the BackupFiles directory on the external usb storage.

In summary, I think I need a way to sync all files (including the directory and sub-directory structure) from the CIFS share onto the external USB storage.

Questions

Is there a way to do this in Ubuntu from the CLI? Will I be prompted to specify the CIFS share username and password?

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