On Thu, 03 Feb 2005 19:27:34 +0000, Steve wrote:

> > I'd still disagree, rsync or rdiff-backup create an exact mirror of
> > the file tree, so you have a backup that is extremely fast to restore
> > from, especially for individual files. If I want an image of the
> > partition,  I'll
> > use partimage as it is several orders of magnitude faster than dd and
> > produces smaller archives.
> >
> > As a backup tool dd is about as friendly as backing up to punched 
> > cards :(

> OK - I also admit that partimage would be a superior choice to dd...
> I guess my only significant point is that a backup that quickly restores
> devices etc. is not addressed best by trying to copy files.  I guess I 
> inferred more from the original subject than you did.  For a "Simple 
> Backup" where you want to duplicate "everything" from one drive to 
> another I remain convinced that you want to copy the partition(s) and 
> not the files - whereas for a more ambitious incremental backup strategy
> of user files we agree that rsync/rdiff approaches may well prove
> superior. 

It depends on what you are insuring against. To cover drive failure, a
partition image is best,and fastest to restore a whole drive. I make
partimage backups from time to time. To insure against operator error,
such as deleting a file, overwriting a working config with a broken one
etc, file based backups are better. So you really need both.

> Among the complications involved with rsync one should
> consider the  potential consequences of a hardware failure during an
> update phase; the  possibility that a file is accidentally deleted and
> the backup is  refreshed before the missing file discovered.

That's an issue with rsync, but not with rdiff-backup, which keeps older
files. You can restore older versions of files, or deleted files for as
long as they stay in the backup.

> For a mail server, I can't help thinking that the ideal solution would 
> be some (possibly bespoke) mechanism to push emails from the primary 
> server to a secondary server (or maybe just a secondary disk) as it 
> arrives (possibly with a queue as necessary) and not to delete data from
> the secondary server when it is deleted from the first, but rather to 
> archive the eldest data regularly in order to ensure the disks do not 
> fill.  This, however, could not be considered a simple backup by most. 
> [Neil - you'd impress me by naming a tool that would do this 'ideal 
> solution' without the need for writing bespoke scripts...]

You can use a procmail rule to send a copy of a mail to a backup file.

:0c:
/mnt/backup/mail/$USER.backup


> Do we still disagree? :-)

Not now, but I'm sure I can think of something, given time ;-)


-- 
Neil Bothwick

Loose bits sink chips.

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