Hi Bowie,

On Wed, Feb 18, 2009 at 12:26:16PM -0500, Bowie Bailey wrote:

> > So, given that, I don't really understand why there is a distinction
> > between a full and an incremental backup.  Shouldn't either one take
> > up the same amount of space?  That is, if you've got few changes on
> > the client, then on the server you're mostly just hardlinking things
> > anyway, right?  So why is there a choice?
> 
> The result is basically the same, the difference is in implementation.
> A full backup will compare the contents of every file on the system to
> see if anything has changed.  An incremental will only check files whose
> change date has been updated since the last backup.
 
The last sentence is only true for non-rsync transfer methods, e.g. smb
and tar. Rsync will detect any files which have been modified or added
since the last run since it works by comparing file lists between server
and client while samba and tar backup methods depend on the file's change
times to detect changes.

> I believe one of the main incremental backup issues is that they do not
> detect deleted files.  Incremental backups are also usually MUCH faster
> than full backups.  For example, one of my backups takes about 600
> minutes for a full backup, but only 56 minutes for an incremental.
 
Incrementals using rsync will detect deleted files correctly. I'm not
sure about samba/tar.

Tino.

-- 
"What we nourish flourishes." - "Was wir nähren erblüht."

www.lichtkreis-chemnitz.de
www.craniosacralzentrum.de

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