[techtalk] RE: backup newbie

Conor Daly conor.daly at oceanfree.net
Wed Nov 29 23:36:57 EST 2000

On Wed, Nov 29, 2000 at 08:11:32AM -0800 or so it is rumoured hereabouts, 
Eric Richard Turner thought:
> On Wed, 29 Nov 2000, Magni Onsoien wrote:
> > Eh, what exactly is the difference between incremental and differential
> > backups?
> With differential, every file that has been changed since the last
> full-system backup is saved. When you restore, all you have to do is
> restore from the full-system backup then from the last differential
> backup. Differential backups are nice because they are simple to restore.
> However, as time increases from the prior full-system backup the
> differential backups take longer.
> With incremental, only files that have been changed since the last
> backup (either full or incremental) are saved. When you restore, you start
> by restoring the full-system backup, then you have to restore each
> incremental backup that has been done since the full-system backup. The
> advantage to this method is that it takes less time to do your backup than
> with differential.
> An example to highlight the difference between the two methods:
> Let's say you do a full-system backup on Sunday. Then a worker modifies
> file x on Monday, and that evening you do a backup. At this point, there
> is no difference between an incremental backup and a differential backup
> because only file x will be backed up. Then on Tuesday a worker modifies
> file y (but not file x). When you do a backup on Tuesday evening, the
> differential backup will backup files x and y, while the incremental will
> only backup file y because you already have a perfectly good backup of
> file x from Monday's backup.
but can I do the following?

1st of Month:          Full backup
Sunday:                Differential Backup from Monthly
Daily:                 Differential Backup from Sunday

Conor Daly <conor.daly at oceanfree.net>

Domestic Sysadmin :-)

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