this post was submitted on 04 Aug 2024
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I use Arch btw


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[–] [email protected] 45 points 1 month ago (5 children)

I think I didn't make it clear enough: My laptop was on the power during the update process, when the power randomly cut out - for the first time in about 6 years, it doesn't happen often. Of course you can interpret it as user error - but I think it's reasonable to update my system when plugged into, normally reliable power. The laptop battery is pretty much dead, so it would've shut itself down automatically anyway.

[–] [email protected] 46 points 1 month ago (5 children)

sure, but what os wouldn't break if you did this?

[–] [email protected] 30 points 1 month ago (1 children)

Just about any Linux I've ever used keeps the previous kernel version and initrd around. And nowadays snapper makes a new snapshot before and after every package installation or update.

So, I'd think there are a lot.

[–] [email protected] 7 points 1 month ago

So what I'm hearing is install Linux-LTS and pacsnap

[–] gaylord_fartmaster 15 points 1 month ago (1 children)

Plus in Linux you can actually fix this with a live USB, while on Windows you can run startup repair and hope for the best.

[–] [email protected] 6 points 1 month ago* (last edited 1 month ago)

In Windows you can also fix this with a live Windows USB, manually.

[–] [email protected] 13 points 1 month ago (3 children)

Windows doesn't in my experience, it's surprisingly robust.

But also I thought Linux distros normally keep the old Kernel around after an update so stuff like this doesn't cause a boot failure?

[–] 9point6 7 points 1 month ago

Yeah windows "cumulative update" upgrades for the past couple of years basically duplicate the whole system directory and apply the update to that leaving the existing one to roll back to if anything fails

[–] [email protected] 2 points 1 month ago* (last edited 1 month ago)

Windows updates (and Windows Installer) are transactional. If the update or installation fails, it knows exactly how to revert back to the previous state.

Windows Installer supports this across multiple packages too - for example, a game might need some version of DirectX libraries which needs some version of the Visual C++ runtime (probably showing my age because I doubt games come bundled with DirectX any more). If one of the packages fails to install, it can handle rolling everything back. Linux can sometimes leave your system in a broken state when this happens, requiring you to manually resolve the issue - for example, on a Debian-based system if the postinst script for a package fails.

[–] [email protected] 1 points 1 month ago (1 children)

But also I thought Linux distros normally keep the old Kernel around after an update so stuff like this doesn’t cause a boot failure?

Arch has no concept of "previous package", so it doesn't do this.

You could install linux-lts (or one of the other alternative kernels) side by side with the linux package, so you always have a bootable fallback, but like most things on Arch it's not enforced.

[–] [email protected] 2 points 1 month ago

That's pretty wild, I guess arch is not meant to hold your hand at all so it makes sense.

[–] [email protected] 11 points 1 month ago (2 children)

Any immutable distro, Debian, Ubuntu, all their derivatives, Fedora, all its derivatives, OpenSUSE, Slackware, ...
Basically, 95+% of installed Linux systems would retain the old or a backup kernel during an upgrade.

[–] [email protected] 3 points 1 month ago

good answer to a bad and uninformed question, thanks.

[–] [email protected] 2 points 1 month ago (2 children)

Any immutable distro, Debian, Ubuntu, all their derivatives

Debian and Ubuntu are not immutable distributions by default, unless I am mistaken.

[–] [email protected] 2 points 1 month ago (1 children)

They weren't saying Debian and Ubuntu are immutable - they were saying "any immutable distro", "Debian", and "Ubuntu" as three separate items in a list.

[–] [email protected] 2 points 1 month ago (1 children)
[–] [email protected] 2 points 1 month ago

Any immutable distro and Debian and Ubuntu and all their derivatives

[–] [email protected] 3 points 1 month ago (2 children)

If it was on something like BTRFS it'd probably be fine, though I imagine there's still a small window where the FS could flush while the file is being written. renameat2 has the EXCHANGE flag to atomically switch 2 files, so if arch maintainers want to fix it they could do

  1. Write to temporary file
  2. Fsync temporary file
  3. Renameat2 EXCHANGE temporary and target
  4. Fsync directory (optional, since a background flush would still be atomic, just might take some time)
[–] [email protected] 1 points 1 month ago

renameat2

I read this as "rena meat 2" and was very confused

[–] [email protected] 0 points 1 month ago (1 children)
[–] kolorafa 7 points 1 month ago

Just having btrfs is not enough, you need to have automatic snapshots (or do them manually) before doing updates and configured grub to allow you to rollback.

Personally, I'm to lazy to configure stuff like that, I rather just pick my Vetroy USB from backpack, boot into live image and just fix it (while learning something/new interesting) than spend time preventing something that might never happen to me :)

[–] [email protected] 24 points 1 month ago

I still don't get the problem. Are you complaining you have to chroot into your system and finish the update because your power got interrupted? Is a 5 min detour into a live system making you unconfortable? This is how you would fix it in any distro except the image based ones and the arch wiki will guide you excellently how to do it. Good luck!

[–] [email protected] 19 points 1 month ago (1 children)

I mean any which way you try to frame this, saying that you won’t use Arch anymore because you didn’t take the precautions necessary based on your situation is gonna take some heat here.

[–] [email protected] 4 points 1 month ago (2 children)

What precaution would you expect OP to would've done though? A fallback kernel would be my guess - that's something many casual oriented distro do out of the box basically. . I read your post as "you're right, don't use arch" - something btw which I tend to agree with although I wouldn't say that's because of the precautions.

I use arch because there's no black box magic. For an end user who expects or wants that... Yes, arch might not be the right choice.

[–] [email protected] 6 points 1 month ago (2 children)

I don't think lack of precaution was the issue here given that it was an unexpected power failure, but it is a fairly easy fix with a chroot.

[–] [email protected] 2 points 1 month ago (1 children)

Oh agreed! That's why I'm with OP actually that arch might not be the right distro to go for.

The person I replied to basically said "that's what you deserve for not doing it properly" if I understood it correctly - that's what I'm confused about as well.

[–] [email protected] 3 points 1 month ago (1 children)

Yeah it seems half the commenters missed OP's clarifying comment and just think he started a kernel update with 2% battery life.

[–] [email protected] 1 points 1 month ago

Hehe true. And even that happened to me after a couple of tired "Syu enter". But then again I learned something new with nearly every repair!

[–] [email protected] 0 points 1 month ago* (last edited 1 month ago) (1 children)

If you know your battery is shot and you don’t have a way to save your install if the power goes out, then you just don’t update. There are plenty of ways to protect against this that have already been mentioned (battery backup, backup kernel, etc). OP was just playing with fire.

[–] [email protected] 5 points 1 month ago

That's kind of overzealous. I would expect most desktop users to run kernel updates without being plugged into a UPS, this is functionally identical. It's not like it's an unrecoverable error, but yeah if you're updating a critical system you should have redundancies in place.

[–] [email protected] 2 points 1 month ago (1 children)

How would you set up a fallback kernel in Arch?

[–] [email protected] 2 points 1 month ago

I have set up an lts kernel in addition to the zen I use by default. See:

https://wiki.archlinux.org/title/Kernel

Disclaimer: this only works when something with image creation goes wrong with an update. Which didn't happen to me ever - unless I did a mistake or tested some kernel stuff. I only had bootloader errors when I screwed up pacman though. The fallback kernel in that case is on a USB stick...

[–] [email protected] 2 points 1 month ago

I don't really get why you couldn't pick one of your other installed kernels and boot that, but you seem pretty intent on blaming arch and I don't feel like trying to troubleshoot it, so that's that I guess.

[–] [email protected] 1 points 1 month ago (1 children)

How dead are we talking here? Even on an older laptop a kernel update doesn't take that long. Should have just kept it going, hoping for the best.

[–] [email protected] 2 points 1 month ago

I am using an old laptop that gives me 3 minutes to run from one power plug to the other before just going out.