Backup feature?

[Peter C. Norton]

On Thu, Aug 03, 2000 at 07:14:24PM +1000, Phillip J Shelton wrote:
> Rather like the tar and dump systems for tape?

Every backup tool has the same goal.  Tar is an archiver, though, not a
backup tool, and dump is also more archive-oriented.  The filesystem log
hack that I've seen done gives you every change to the filesystem in your
backup, allowing you to roll forward and roll back through every change made
to the filesystem.  

> > IMO a log-based filesystem should be able to be extended (maybe
> > special-purpose, maybe generally) do this - at the cost of a lot of extra
> > space - and that way let you look at past snapshots of your files, too.  In
> > principle if a filesystem is treated as a constantly updated, linear log,
> > the log changes can be backed up to any device.  a cd r/w would be a good
> > one.
> 
> CVS and RCS keep a copy of you old changes don't they? Hmm, if you were going
> to insist on keeping absolutely every change as a separate snapshot it would
> very quickly get quite high version numbers.

No, only for text files.  The gnu difflib, last I looked, doesn't know how
to deal with differences in binary files.   Which makes a lot of sense.
Outside of structured documents it's unlikely that you can really diff
binary files in a generally useful way.

-- 
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In five years we'll make up another plan.
Or just re-use this one.