Re: [Duplicity-talk] Resumption and fulls with large backups.

[Kenneth Loafman]

Robin Lee Powell wrote:
> On Tue, Aug 11, 2009 at 01:13:48PM -0500, Kenneth Loafman wrote:
>> A full backup, by definition, backs up all the files, so yes, a full
>> backup copies all the files.  
> 
> Yes, but many backup system look at the previous full, and keep
> files that haven't changed, without retransmitting.  We're talking
> about 700 GiB of data; copying all of 700GiB (to S3 no less) takes a
> *very* long time.

I don't know of those backup systems.  Without something on the remote
to manage the backup volumes, the overhead of removing the deleted files
from each volume would be more than retransmitting the new volume.  We
do not run anything on the remote system.

> A full, by definition, has all the files within it, but that's not
> necessarily the same thing as retransmitting all of them.

If we could remove the the old from the unchanged in the volumes on the
remote, that might be possible.  For now, the overhead of getting to the
remote is the gating factor.  For us its not a matter of just remotely
deleting old files and leaving the unchanged ones in place.

> We're only copying the data generated by the application; we're not
> touching the OS at all.

That's a fair amount of data.

...Ken

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