Re: Identifying which files changed between archives

[Jacob Larsen <jacob@larsen.net>]

I had the same issue a while back. I was told it was not easily fixed 
due to the layers in Tarsnap. I ended up making a regular tarball and 
fed that to tarsnap. That way I had a local tarball that matched the 
actual data in the archive. Then I could extract it and compere at the 
next backup. A bit data heavy process but it gave me what I needed. It 
is scriptable, so it is possible to let your backup script log the 
changed files on each backup run, but it has a pretty high cost in disk 
I/O, plus you need to keep a copy of your data around between backups.

/Jacob

On 18/06/2019 13.49, Scott Dickinson wrote:
> Hi,
>
> I'm trying to work out how to generate a report on files that are new 
> or changed in a particular archive. I can't seem to find an easy way 
> to do this, so hoping someone can help.
>
> Here is the scenario I'm working through.
> 1. Backup directory "x" on 1st May 2019. First time archive, all 10Gb 
> are sent as expected.
> 2. Backup directory "x" on 1st June 2019. Second time archive, 25Mb 
> are sent.
>
> How can I report on which files that 25Mb of delta's are part of? In 
> this scenario, I wasn't expecting any changes to the files over the 
> month, so am surprised there were anything above the metadata to be 
> backed up. My understanding is that Tarsnap needs to know which files 
> the changed blocks belong to, therefore in theory this metadata should 
> be extractable.
>
> The closest I've found to locate this is "tarnsap -t -f 'x' -v 
> --iso-dates", but this doesn't natively provide the details I'm after. 
> Ideally I'd like tarsnap to be able to report which files were 
> uploaded at the time or archive with an option similar to --print-stats.
>
> Anyone got any ideas?
>
>
> Cheers,
> Scott