Re: NAS Backup solution?

On Mon, 23 Jun 2025 18:51:18 +0100, The Natural Philosopher wrote:

On 23/06/2025 11:25, Chris Elvidge wrote:

>
I use rsync regularly to backup remote systems using ssh, where
known_hosts and authorized_keys are correctly populated (eg):
rsync $OPTIONS remotehost:/ localdir/
to copy a whole remote host to a local directory system.
>

I also do this with an rsyncd on the far end ...

I’ve never found a use for rsyncd. All my network-based rsyncs have
been point-to-point connections via SSH.

Regarding the --link-dest option, here’s how you might use it.

First backup:

    rsync «options» «remotehost»:«dir» «local-backup-root»/«backup1»/

(This will be a full backup.)

Next backup:

    rsync «options» --link-dest=«local-backup-root»/«backup1»/ \
        «remotehost»:«dir» «local-backup-root»/«backup2»/

This avoids re-copying any files that haven’t changed since the
previous backup, so the additional disk space needed would be the same
as for an incremental backup. However, the clever thing is, the result
still looks like a full backup for restoration purposes.

Typically the names «backup1», «backup2» etc will have a timestamp
somewhere in them, as an obvious way to have unique names that also
mean something.

And so on:

    rsync «options» --link-dest=«local-backup-root»/«backup2»/ \
        «remotehost»:«dir» «local-backup-root»/«backup3»/

When you get to 7 backups (or whatever your desired limit of old
versions is), you can get rid of the oldest remaining one as you do a
new one:

    rm -rf «local-backup-root»/«backup1»/

and continue from there. Files that were superseded in later backups
will disappear, while those that were not will remain.