Still looking for a usable NAS for Ubuntu 23.04

[Karl Auer]

On Mon, 2023-08-07 at 12:02 +0100, Chris Green wrote:
> If/when you need the backup it means the system you are backing up
> has failed, as long as the NAS is working (you do check regularly?)
> then you have your backup and can restore your files.

That's certainly not true in my case. What's on my computer is a
relatively small subset of what's on the NAS, plus whatever has not yet
been backed up, plus a bunch of stuff that I don't bother backing up
(the operating system for a start).

Or put the other way, there is a huge amount of stuff on the NAS that
is not on my computer.

Particular examples of things not on my computer include a music
library, a film library, a wiki, an archive of things I access rarely
but need to keep - this list goes on. For all those things, the NAS is
not a backup, it's the master copy. This is a very typical usage
pattern for general purpose networked storage.

Hence my statement that a NAS is not (on its own) a backup.

> Similarly if the NAS dies then your files are still on the system
> it's backing up so you are still OK.

Nope. If my NAS died and I had no backups of it, I would unrecoverably
lose terabytes of data.

> Yes, further backups are better but I don't really understand what
> you mean by "a NAS is not a safe backup on its own".

Hopefully the above makes it clearer. The NAS itself needs to be backed
up, or at least the bits of it you don't want to lose need to be backed
up.

It's not just because the NAS has the master copy of lots of things.
The NAS is also very likely in the same house as things that are
backing up to it - if the house gets burned down (or whatever), both it
and the things backing up to it will be lost.

Another reason why a NAS is not a good backup is that a NAS is
generally permanently connected and accessible to client systems as a
file system. If a client computer gets infected with malware or
ransomware, anything the client can write to can be affected. You want
to be keeping copies of the data that are not directly accessible.

A slightly more subtle reason why a copy of a file on a NAS is not a
backup (or not a good one) has to do with versioning. If your backup
consists of copying some vital file to the NAS, and every time you copy
that file you overwrite the copy on the NAS, then you have no
protection against accidentally overwriting the wrong file. And no
protection if the file is corrupted (e.g. by ransomware) and you don't
notice until after you've copied it. Backups need to be versioned, as
deeply as possible.

> Ultimately no number of backups can be entirely foolproof but one is
> way better than none, and then two is a bit more better and so on.

You are right that it is a continuum, but for many situations the NAS
is not even one backup; see above. 

> In some ways it's more important *where* the backup is than what it
> is.  A backup on a drive within the system being backed up is not so
> good as a backup on a separate system, then that is not so good as a
> remote backup, etc.

All true. You should have at least one backup that will not share the
same fates as may befall the others. It should be not in the same
computer, not connected to the same computer, not on the same network
as the other computers, not in the same building, ideally not in the
same street, town, city or country... you get the idea.

Most people can find a way to get at least one backup stored outside
the house or business premises.

For those interested, my systems get backed up nightly to a NAS, and
the NAS backs itself up nightly to a permanently connected external USB
drive. The nightly NAS backups are versioned, 99 days "deep"; with each
new nightly backup, the oldest one is deleted. At roughly weekly
intervals everything on that drive gets backed up to another external
drive which is then taken off site, with the previous off-site backup
coming back for re-use. The external drives are not accessible to
client systems, only the NAS (i.e. they are not exported as
filesystems).

The off-site backup drives are versioned indefinitely. When they get
full they are taken out of active service, are archived, and a new
drive is introduced. It's all automatic except that I have to manually
plug and unplug the second-level backups and transport them off-site.
The off-site location is very near somewhere I have to visit frequently
anyway, so it is very little extra effort to take a drive along with
me.

Regards, K.

-- 
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Karl Auer (kauer at biplane.com.au)
http://www.biplane.com.au/kauer