On 21/01 10:48:50, Tino Schwarze wrote:
> On Wed, Jan 21, 2009 at 02:08:31PM +0900, Peter Wright wrote:
> > > An incremental backup will transfer changed data from the
> > > previous full or incremental of a lower level.
> > 
> > Can backuppc be configured to transfer changed data from the previous
> > incremental of the *same* level, or would this require a patch?
> 
> Why would you want to do that? The previous incremental of the same
> level is a lot older and you'd need to transfer a lot more changes.

Take my words in the context of responding to Adam - though perhaps I
could have put it more clearly :).

Adam stated that "An incremental backup will transfer changed data
from the previous full or incremental of a lower level."

What I was thinking is that if my highest priority was minimising
bandwidth per backup, why shouldn't I be able to configure backuppc to
*only* do incrementals and consider them all to be the same "level"?


But I suspect I've probably misunderstood one or more key backuppc
principles, especially re: what the "levels" really mean.

> In default configuration (IIRC), your backups with weekly full would
> look like this:
[ snip description ]
> The second level-1 incremental will transfer all changes since the
> full backup.

Thanks for the clarification - that was how I thought it worked, but
it's good to make sure.

My key issue is that if I'm interested in bandwidth minimisation above
all else, why would I want to do anything other than
incremental-since-the-most-recent-previous-incremental, regardless of
the "level" concept?


As I understand Holger's earlier response, the major (only?) downside
is the cost of building the backup view - and I can certainly see how
that'd become significant after a while.

I suspect I've got my brain too hooked into the rsnapshot model
(http://www.rsnapshot.org/) and I'm not quite understanding the
different philosophy of backuppc.

> Tino.

Pete.
-- 
"But now I've taken my leave of that whole sick, navel-gazing mess we
called the software industry. Now I'm in a more honest line of work:
now I sell beer."  -- jwz

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