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[Aaron Whitehouse <question116587@xxxxxxxxxxxxxxxxxxxxx>]

Question #116587 on Duplicity changed:
https://answers.launchpad.net/duplicity/+question/116587

    Status: Answered => Open

Aaron Whitehouse is still having a problem:
Peter,

Thanks again for all of your help.

Yes, I knew that was an example-I provided the other text in my initial post. To me, that text wasn't clear and that is why I posted this question. It seems to focus too much on things that have changed since the last backup, which I would have thought would be better found by running your normal backup command with the --dry-run option. What I understand "verify" does over and above that is test the integrity of the remote archives, which isn't really mentioned in the man page. If nothing else, it uses "verify" in the definition. Maybe something like the below would be better:
"
verify   Enter verify mode instead of restore, to test the integrity of your remote archive
            files without replacing any local files. Duplicity will download the archive files 
            from the remote location, decompress and decrypt them, and compare them
            to the local copy of the files. This will both inform you if any files have changed
            in either location since the last backup (on verbosity level 4 or higher, duplicity 
            will log a message for each file that has changed) and will alert you to any 
            problems in restoring your remote backup (for example, if one of your remote archives
            has corrupted). If the --file-to-restore option is given, duplicity will restrict verify 
            to that file or directory. Duplicity will exit with a non-zero error level if any files are
            different or if the remote archive(s) could not be successfully compared.

The following command compares the files backed up to the remote
location to the local version of the files. This will tell us what, if
anything, has changed since the last backup and will confirm that the
remote files could be successfully restored:

    duplicity verify scp://uid@xxxxxxxxxx/some_dir /home/me 
"

If you agree with these changes, please let me know and I will file
another bug suggesting the changes to the man page.

As you have already made clear, there are two issues here. The first is
what duplicity is meant to do. It sounds like we agree that it should
provide a means of testing the remote archive files can successfully
restore, without actually restoring and replacing your local files with
the remote ones. If that is what the command is meant to do, I would
suggest that the man page make that clearer, as set out above.

The second issue is that it sounds as though it isn't currently doing
that properly. A tool that purports to verify everything but doesn't do
so is worse than no tool at all, so thank you very much for filing the
bugs about the problems. Presumably I could write some script that ran
through each file that was backed up, do a "--file-to-restore" to a temp
file, compare that restored file to the original, delete that file and
move on to the next one. That seems silly when it can be, and already is
mostly, in duplicity itself. As far as you know, Peter, would
duplicity's "verify" command (with your bugs fixed) give me an
equivalent level of comfort as this imaginary script, or are there other
issues with the "verify" option?

I hope that I don't come across as critical. I love duplicity and that
is why I'm keen to see it be the default backup program for everything
(with the deja dup frontend or similar for desktop distributions).
Unlike simply copying files to an external HDD and being able to just
check the copy, duplicity files are like random chunks of data. So I get
a little nervous that, despite my regular duplicity backups, I'll get
caught out when I finally need to rely on the backups. There are enough
bugs filed about failed restores to give me some slight hesitation.

So hopefully we can make the verify option the perfect compliment to the
backup and restore options, allowing everyone to easily test that they
are safe.

Keep up the great work everyone!

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