Rsync and Cygwin based backup on Windows gives permission denied errors

Background

I use rsync/cygwin on Windows 10 to backup all my local files (source) to an external hard drive (destination). I used this guide http://www.howtogeek.com/175008/the-non-beginners-guide-to-syncing-data-with-rsync/ as a tutorial on how to use rsync/cygwin for backing up. Note: My external hard drive is formatted to NTFS.

On the very first backup, I manually copied/pasted the desired folders to the destination. All subsequent backups are done using rsync as described below.

My backup method using rsync/cygwin

On Windows, I created a backup.bat file with my rsync commands so I can can quickly plug in my external drive and start the backup. Below is an example of my backup.bat file, where C is my local drive, and E is my external drive.

pause
rsync -avhP --delete --log-file="/cygdrive/C/Users/MyUsername/rsync-backup-log.txt" "/cygdrive/C/Users/MyUsername/Folder A" "/cygdrive/E/Backup/"
rsync -avhP --delete --log-file="/cygdrive/C/Users/MyUsername/rsync-backup-log.txt" "/cygdrive/C/Users/MyUsername/Folder B" "/cygdrive/E/Backup/"
rsync -avhP --delete --log-file="/cygdrive/C/Users/MyUsername/rsync-backup-log.txt" "/cygdrive/C/Users/MyUsername/Folder C" "/cygdrive/E/Backup/"
pause

To ensure I don't have permission issues, I edited my C:\cygwin64\etc\fstab file to below:

none /cygdrive cygdrive binary,posix=0,user,noacl 0 0

Problem/issue

The issue I am having is that I often see "Permission denied (13)" errors. Below is an extract of the rsync log. Notice how some files/folder are backed up without errors. However, there are some files/folders that give permission errors.

...
2016/12/17 15:57:04 [2968] >f+++++++++ Documents/Subfolder A/IMG_5678.JPG
2016/12/17 15:57:04 [2968] >f+++++++++ Documents/Subfolder A/IMG_5679.JPG
2016/12/17 15:57:04 [2968] >f+++++++++ Documents/Subfolder A/IMG_5680.JPG
2016/12/17 15:57:04 [2968] >f+++++++++ Documents/Subfolder A/IMG_5681.JPG
2016/12/17 15:57:04 [2968] >f+++++++++ Documents/Subfolder A/IMG_5682.JPG
2016/12/17 15:57:04 [2968] >f+++++++++ Documents/Subfolder A/IMG_5996.JPG
...
2016/12/17 15:58:03 [6052] >f+++++++++ Folder B/Subfolder C/FileD.docx
2016/12/17 15:58:03 [6052] cd+++++++++ Folder B/Subfolder C/Subfolder E/
2016/12/17 15:58:04 [6052] >f+++++++++ Folder B/Subfolder F/FileG.docx
2016/12/17 15:58:04 [6052] rsync: mkstemp "/cygdrive/E/Backup/Folder B/Subfolder C/.FileD.docx.dBBzQZ" failed: Permission denied (13)
2016/12/17 15:58:07 [6052] rsync: mkstemp "/cygdrive/E/Backup/Folder B/Subfolder F/.FileG.docx.8DkCUR" failed: Permission denied (13)
2016/12/17 15:58:07 [6052] rsync: recv_generator: mkdir "/cygdrive/E/Backup/Folder B/Subfolder H/Subfolder J" failed: Permission denied (13)
2016/12/17 15:58:07 [6052] *** Skipping any contents from this failed directory ***
2016/12/17 15:58:07 [6052] >f+++++++++ Folder B/Subfolder H/FileK.xlsx
2016/12/17 15:58:07 [6052] cd+++++++++ Folder B/Subfolder H/Subfolder J/
2016/12/17 15:58:07 [6052] rsync: mkstemp "/cygdrive/E/Backup/Folder B/Subfolder H/.FileK.xlsx.WQa396" failed: Permission denied (13)
2016/12/17 15:58:07 [6052] sent 91.52M bytes  received 1.79K bytes  9.63M bytes/sec
...

Troubleshooting

To troubleshoot, I navigated to one of the folders with the permission error in Windows Explorer (on the external hard drive). Below is a screenshot of the dialog notification I get. When I click Continue to gain permission, the folder opens, but its empty. When I re-run rsync command (backup.bat), the files in that folder are properly backed up without error.

Screenshot:

Solution 1:

I managed to find a solution which currently works for me. I am unsure if this is a guaranteed correct approach.

In order to avoid permission issues, I need to add the following to my rsync command: --no-p --chmod=ugo=rwX. Thus, my rsync backup command should look like the following:

rsync -avhP --no-p --chmod=ugo=rwX --delete --log-file="/cygdrive/C/Users/MyUsername/rsync-backup-log.txt" "/cygdrive/C/Users/MyUsername/Folder A" "/cygdrive/E/Backup/"

Credit to this solution goes to the following answer in a similar post: https://superuser.com/a/69764/607501

Solution 2:

As you have already indicated, --no-p with --chmod=ugo=rwX will set all permission bits.

However, if you want more fine-grain control over the permissions for the new directory, you can use other arguments for --chmod=

The guide you linked actually has an example of this (may have been added after you used it): --chmod=Du=rwx,Dgo=rx,Fu=rw

man rsync contains lots of information about this option.