Re: deduplicating file systems: VDO with Debian?

[hw <hw@adminart.net>]

On Tue, 2022-11-08 at 10:04 -0500, The Wanderer wrote:
> On 2022-11-08 at 09:36, Nicolas George wrote:
> 
> > Curt (12022-11-08):
> > 
> > > Redundancy sounds a lot like a back up.
> > 
> > RAID also sounds a lot like a backup, and the R means redundant.
> > 
> > Yet raid is not a backup.
> 
> That depends on which sense of the word "backup" you are using.
> 
> No, it's not a "backup" in the technical "back it up to tape" sense of
> the word. There are many types of data-loss scenarios in which it will
> not protect you at all.
> 
> But it does mean that if one drive fails, you can still fall back to the
> copy on the other drive, and thus that copy is serving as a backup to
> the copy on the first drive. There are some data-loss scenarios in which
> RAID will protect you.
> 
> That more general sense of "backup" as in "something that you can fall
> back on" is no less legitimate than the technical sense given above, and
> it always rubs me the wrong way to see the unconditional "RAID is not a
> backup" trotted out blindly as if that technical sense were the only one
> that could possibly be considered applicable, and without any
> acknowledgment of the limited sense of "backup" which is being used in
> that statement.

RAID is like the incarnation of (having) something to fall back on.  Backups
aren't.