Feature proposal: backup classes

Martin Atkins mart at degeneration.co.uk
Wed Apr 8 07:47:27 UTC 2009

What is the use-case for this?

In my (admittedly limited) experience, classes of backups have been used 
either where there is a variety of backup media with different 
characteristics available, or where different datasets are being backed 
up to the same target.

I'm having trouble imagining why you'd want to distingish "classes" of 
backup from the same source to the same medium.

Can you elaborate a bit on what you're trying to achieve?

(If you *are* talking about different media, then presumably this 
problem can be solved with different backup sources and targets. Your 
example at the end of having backups with "daily" and "monthly" in their 
names seems functionally equivalent to having three sources called 
"home", "home-daily" and "home-monthly" and pruning the backup files 
based on name, periodically running a gc to remove orphaned chunks.)

Gavin Carr wrote:
> One feature that's available in most other backup systems, and
> currently missing in brackup, is the ability to distinguish 'classes'
> of backup (like monthly/weekly/daily), and prune or rotate separately
> within those classes. 
> I'd like, for instance, to able to tag the first backup of the month 
> as a 'monthly', and have those backups ignored in the standard prune.
> Or do monthlies and weeklies and dailies, say, and keep all monthlies, 
> 8 weeklies, and 30 dailies, or whatever.
> I think this would just be a matter of adding the notion of a 'class' 
> to a backup, and modifying prune to be class-aware (perhaps initially 
> just operating on a single class). I'd imagine you'd keep the current
> behaviour by allowing a 'null' class that's used if one isn't 
> specified.
> I believe brackup-target list_backups and prune just look at the 
> brackup file name and metadata rather than looking at its contents, so 
> we probably want to encode a classname in the brackup filename to 
> keep this behaviour. Perhaps we could just append a class, if given,
> to the brackup file name, like this:
>   home-1233494128.brackup
>   home-1233548070-daily.brackup
>   home-1233704988-monthly.brackup
> which would display in list_backups as:
>   home-1233494128           Mon 02 Feb 2009 00:20:12         31034846
>   home-1231679729-daily     Mon 12 Jan 2009 00:20:01         30507171
>   home-1228050927-monthly   Mon 01 Dec 2008 00:19:10         29264710
> Thoughts/comments? 
> I'm happy to produce some code if there's general agreement on the 
> concept.
> Cheers,
> Gavin

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