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I currently have Ubuntu 16.04 installed. I intend to erase disk and perform a clean install of Ubuntu 20.04 from a bootable USB flash drive. If I were to backup my files using Deja Dup in 16.04, would I be able to restore these files in my fresh install of 18.04? Any known problems?

Edit: I am looking to use Deja Dup and its encryption feature, so the traditional copy paste files is not an option.

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    It is best to test it before doing anything drastic. Here is a way to test. 1. Create a test file called restoretest.txt in your /home/$USER folder. 2. Backup using Deja Dup to an external drive. 3. Boot from the Ubuntu 20.04 installation USB using the Try Ubuntu option. 4. Open Deja Dup and restore the file test file restoretest.txt from the external drive. – user68186 May 6 at 13:10
  • @user68186 It's a good trial and error based suggestion, however I am not sure if its possible to account for diverse file formats and sizes. Will take a longer time to make this validation. – Jugesh Sundram May 7 at 10:42
  • As @vanadium says the concern is incompatible changes between versions of deja dup. If one file can be backed up using the old version and restored using the new version then I assume all files can be restored. If your concern is various file types and sizes being backed up, then I will vote this question to be closed as "opinion based", as no one in this world has the exact same personal files as you. Even if someone answers and says they did exactly what you want to do and it worked, it may not work for you if your backup has other file types and sizes. – user68186 May 7 at 13:11
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An Experiment

I tested whether encrypted backup made by Deja Dup, the default backup app, in Ubuntu 16.04 can be restored using the Deja Dup app that comes with Ubuntu 20.04.

The Methodology

I created two virtual machines in QEMU/KVM running on the host Ubuntu 20.04 desktop, from the two ISO files:

  1. ubuntu-16.04.7-desktop-amd64.iso
  2. ubuntu-20.04.2.0-desktop-amd64.iso

These are two separate full and complete installations of Ubuntu on two separate virtual disks.

I Connected both VMs, VM-16.04 and VM-20.04, to the host computer's public folder /home/$USER/Public at the respective mount points /mnt/Public.

The Backup Process in VM-16.04

I Created /mnt/Public/backup from the VM-16.04.

I Created three files:

  1. testrestore16.04.txt
  2. testrestore16.04.ods
  3. testrestore16.04.odt

at the /home/$USER/Documents folder in the VM-16.04. Each file contained a single line:

This file is to test if files backed up in Ubuntu 16.04 can be restored in Ubuntu 20.04.

I Set up Deja Dup Storage Location to /mnt/Public/backup and clicked the Backup Now... button.

I assigned an encryption password when prompted.

When the back up was complete, I turned off the VM-16.04.

The Restore Process in VM-20.04

I turned on the VM-20.04.

I Made sure the host /home/$USER/Public was mounted as /mnt/Public in the VM-20.04.

I opened Deja Dup and started the restore process by clicking on the the Restore... button.

Restore from where? I set the Backup location as "Local Folder" and folder as /mnt/Public/backup.

Restore from when? Date: 05/07/2021

Restore to where? Restore files to original locations

I read the Summary page and made sure the information was correct and pressed the green Restore button.

At the Ecryption Password Needed page I provided the backup encryption password.

Results

First, the restore process of "the backup taken in Ubuntu 16.04" completed in Ubuntu 20.04 without any errors.

Second, The folder /home/$USER/Documents was empty before the restore. Three files,

  1. testrestore16.04.txt
  2. testrestore16.04.ods
  3. testrestore16.04.odt

appeared in the /home/$USER/Documents folder of Ubuntu 20.04 after the restore.

Third, I opened the file testrestore16.04.txt in Gedit and the following text was legible:

This file is to test if files backed up in Ubuntu 16.04 can be restored in Ubuntu 20.04.

I wrote a single word, "Success" to the text file, and the file was saved successfully proving that the file was readable and writable. The same process was followed for the other two files, testrestore16.04.ods, and testrestore16.04.odt using the LibreOffice Calc and Writer apps respectively.

Conclusion

Based on this limited testing the experiment was a resounding success. I conclude that plain text, and LibreOffice Calc, and Writer files backed up with encryption by the default version of Deja Dup that comes with Ubuntu 16.04 can be fully restored by the Deja Dup that comes with Ubuntu 20.04.

Hope this helps

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    Thank you for putting the effort to shed some light into this uncertainty. – Jugesh Sundram May 8 at 7:31
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In principle, yes.

Very likely yes, but afaik this is not 100% guaranteed. You are backing up your data with an older version of Dejadup, you will be restoring it with a newer version. There is an (albeit very unlikely) chance that a newer version may have changed internal workings, and may be incompatible with your backup.

That chance is very, very little, though. One can trust that the developers of this backup tool will do everything possible to maintain compatibility with older backups. In addition, the backup tool uses standard and open formats for the storage of the backup, i.e., pgp encrypted content in standard tar archives. So even if the tool would change or go away, the standard long standing and well developed command line tools that can open these archives, certainly will remain available.

Still, I personally would feel saver making a direct copy of the files on a linux file system that supports linux file permissions. Then, you have the backup in files that can be directly copied. Plain copying of files and file attributes is guaranteed to work in a newer version of the operating system.

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  • Thank you for your quick response. It is the trust aspect that makes the whole process uncertain. I am looking out for responses from people that have actually tried backing up on 16.04 and successfully restoring on 18.04 using Deja Dup. I agree traditional copy paste can be a solution but you lose out on the ability to encrypt data - which Deja Dup allows you to do. – Jugesh Sundram May 7 at 10:48
  • You did not indicate this in your question. You will get the same answer of people who did this trajectory specifically. Essentially, the answer is "Yes, you can". Yes, it is a matter of trust, like for any software. In this case, this is more critical because it concerns all of your personal data. – vanadium May 7 at 15:41

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