Re: reinstallation and restore after catastrophic mistake or failure; was: 1 Currently unreadable (pending) sectors How worried should I be?
On 6 Jan 2024 00:37 -0800, from dpchrist@holgerdanske.com (David Christensen):
> I suggest taking an image (backup) with dd(1), Clonezilla, etc., when you're
> done. This will allow you to restore the image later -- to roll-back a
> change you do not like, to recovery from a disaster, to clone the image to
> another device, to facilitate experiments, (such as doing a secure erase to
> see if it resolves the SSD pending sector issue), etc..
>
> If you also keep your system configuration files in a version control
> system, restoring an image is faster than wipe/ fresh install/ configure/
> restore data.
I would go even farther. Backups should be designed such that
recovering from a catastrophic storage failure, such as getting hit by
ransomware, unintentionally doing a destructive badblocks write test
or the sudden failure of a storage device, is possible by at most
something very similar to:
* Boot some kind of live environment
* Set up file systems on the storage device to be restored onto
(partitioning, setting up LUKS containers, formatting, whatever else
might be called for)
* Within the live environment, install and configure the software
needed to access the backup (if any) (this may include things like
cryptographic keys, access passphrases and the likes)
* Perform the restoration from the most recent backup (this is the
part that likely will take a significant amount of time)
* Update the restored copies of /etc/fstab, /etc/crypttab and any
other files that directly reference the partitions or file systems
by some kind of ID (UUID, /dev/disk/by-*/*, ...)
* Reinstall the boot loader
* Reboot
* Reinstall the boot loader again from within the restored environment
to ensure that everything relating to it is in sync
Such recovery should _not_ need to involve significant reconfiguration
of anything. Any such requirements will massively increase your time
to recovery, as I think we're seeing an example of here. And yes,
pretty much all of this could be scripted, but I strongly suspect that
few people need to do a bare-metal restore of their most recent backup
often enough for _that_ to be worth the effort to create and maintain.
Which is not to say that keeping configuration files
version-controlled cannot provide benefits anyway; but given a proper,
frequent backup regime, the benefits even of that are reduced.
--
Michael Kjörling 🔗 https://michael.kjorling.se
“Remember when, on the Internet, nobody cared that you were a dog?”
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