[Bacula-users] feature suggestion: convert old full backups to "reverse" incremental backups

[Gavin M. <gav...@gc...>]

Hi,

I'm not sure if this suggestion is well-known already, implemented already
or maybe just a plain stupid idea that wouldn't work.  So, I'm going to
suggest it and don my flame-retardant suit.   Feel free to flame or shoot
it down.

Suppose I do monthly full backups with differentials and incrementals in
between.  I'd like to hold onto many years of monthly snapshots.  A file
which is in the backups unchanged the entire time will be duplicated 12
times each year.  This is kind of wasteful and will be expensive.  What I'd
prefer to do is keep a series of full backups (say 6 months worth) and keep
monthly incrementals or differentials which allow me to get back to earlier
snapshots.

I think this might be doable by, every month, running a (new?) type of
migrate job which takes the oldest two full datasets (fb_t0 and fb_t1) and
creates an incremental dataset (ib_t1t0) which, applied to fb_t1 would give
the older dataset.  You would then recycle the fb_t0 dataset but the full
data would still be available via the incrementals.  A month later the same
process would happen with fb_t1 and fb_t2.  fb_t0 would then be available
via fb_t2, ib_t1t0, ib_t2t1.  Over the years, making your way back to the
start would become a longer and longer process, but at least it would still
be possible.

This seems somewhat similar to the new virtual backup feature (which is a
brilliant one, might I add).

All suggestions, corrections and criticisms welcome,

Gavin

PS if further background is required, see the first three paragraphs of
this earlier thread.

http://www.mail-archive.com/bac...@li.../msg36365.html