Hi Spencer,

I haven't tested it but I think a better solution to your issue would be to create a RAID1 with both hard disks. This way the kernel will keep both in sync automatically and you don't need to dd every night. If one fails the raid will be degraded but still bootable so you can just use mdadm to insert a new drive and sync everything back . Though, while read performance will remain the same, you will have slower write throughput. 

Cheers patrick

Spencer Collyer <spencer@spencercollyer.plus.com> schrieb am So., 30. Okt. 2022, 12:44:

This is sort-of a follow-on to my earlier message regarding how to best
set up a new desktop to match the existing one I have running Arch.

I'm intending that my new computer will have an M2 drive as the boot
disk. As well as the OS it will also hold my /home partition.

Because of a bad experience I had with a Windows laptop with an SSD
drive installed, where the SSD got completely wiped back to its factory
setting, my intention is to have a hard disk that acts as a 'shadow' of
the boot disk. The idea is it will also be a bootable drive with
exactly the same setup as the M2 drive. That way if the M2 drive dies,
I can still boot using this backup drive and the system will look the

My intention is to have a cron job that periodically (at least daily)
synchronises the backup drive so it looks exactly the same as the main

Does that sound like a feasible plan?

If it is, my question is what is the best way to initially set up the
shadow drive? Should I do a full install on it, so almost treating it
like I'm setting up a new computer, but making sure I have all the same
packages and setup as the main drive. Or should i just use 'dd' to copy
the whole main drive over to the backup drive? I'll make sure the two
drives are the same size (or rather that the backup is at least as
large as the main drive). Or is there another, better, way I haven't
thought of or found while trawling the web?

Thanks for your attention,