this post was submitted on 01 Aug 2024
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I use Arch btw


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[–] [email protected] 152 points 2 months ago (12 children)

Cleanup

Check current disk usage:

sudo journalctl --disk-usage

Use rotate function:

sudo journalctl --rotate

Or

Remove all logs and keep the last 2 days:

sudo journalctl --vacuum-time=2days

Or

Remove all logs and only keep the last 100MB:

sudo journalctl --vacuum-size=100M

How to read logs:

Follow specific log for a service:

sudo journalctl -fu SERVICE

Show extended log info and print the last lines of a service:

sudo journalctl -xeu SERVICE

[–] [email protected] 38 points 2 months ago (1 children)

I mean yeah -fu stands for "follow unit" but its also a nice coincidence when it comes to debugging that particular service.

[–] [email protected] 4 points 2 months ago
[–] [email protected] 23 points 2 months ago (1 children)

--vacuum-time=2days

this implies i keep an operating system installed for that long

[–] [email protected] 9 points 2 months ago

something something nix?

[–] slazer2au 19 points 2 months ago

sudo journalctl --disk-usage

panda@Panda:~$ sudo journalctl --disk-usage  
No journal files were found.  
Archived and active journals take up 0B in the file system.

hmmmmmm........

[–] [email protected] 12 points 2 months ago* (last edited 2 months ago) (1 children)
user@u9310x-Slack:~$ sudo journalctl --disk-usage  
Password:  
sudo: journalctl: command not found  
[–] [email protected] 20 points 2 months ago* (last edited 2 months ago) (1 children)

seems like someone doesn't like systemd :)

[–] [email protected] 5 points 2 months ago (1 children)

I don't have any feelings towards particular init systems.

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

Just curious, what distro do you use that systemd is not the default? (I at least you didn't change it after the fact if you don't have any feelings (towards unit systems ;) ) )

[–] [email protected] 5 points 2 months ago
[–] [email protected] 9 points 2 months ago

Badass! Thanks!

[–] Tekkip20 8 points 2 months ago (2 children)

Thank you for this, wise sage.

Your wisdom will be passed down the family line for generations about managing machine logs.

[–] [email protected] 5 points 2 months ago

Glad to help your family, share this wisdom with friends too ☝🏻😃

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[–] Pacmanlives 3 points 2 months ago (5 children)

Actually something I never dug into. But does logrotate no longer work? I have a bunch of disk space these days so I would not notice large log files

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[–] [email protected] 3 points 2 months ago

If you use OpenRC you can just delete a couple files

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[–] [email protected] 31 points 2 months ago (1 children)

Try 60GB of system logs after 15 minutes of use. My old laptop's wifi card worked just fine, but spammed the error log with some corrected error. Adding pci=noaer to grub config fixed it.

[–] xilophor 24 points 2 months ago (1 children)

I had an issue on my PC (assuming faulty graphics driver or bug after waking from sleep) that caused my syslog file to reach 500GiB. Yes, 500GiB.

[–] [email protected] 10 points 2 months ago* (last edited 2 months ago) (1 children)

Nearly 700gb in logs

wtf 🤯

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[–] [email protected] 30 points 2 months ago (1 children)

You just need a bigger drive. Don't delete anything

[–] b00m 10 points 2 months ago

Oh lord watch me hoard

[–] [email protected] 30 points 2 months ago* (last edited 2 months ago) (1 children)
[–] Ironfacebuster 5 points 2 months ago (1 children)
[–] [email protected] 5 points 2 months ago

Ah, yes, the standard burger size.

[–] hushable 26 points 2 months ago* (last edited 2 months ago)

Once I had a mission critical service crash because the disk got full, turns out there was a typo on the logrotate config and as a result the logs were not being cleaned up at all.

edit: I should add that I used the commands shared in this post to free up space and bring the service back up

[–] [email protected] 25 points 2 months ago* (last edited 2 months ago) (2 children)

Fucking blows my mind that journald broke what is essentially the default behavior of every distro's use of logrotate and no one bats an eye.

[–] [email protected] 25 points 2 months ago* (last edited 2 months ago) (2 children)

I'm not sure if you're joking or not, but the behavior of journald is fairly dynamic and can be configured to an obnoxious degree, including compression and sealing.

By default, the size limit is 4GB:

SystemMaxUse= and RuntimeMaxUse= control how much disk space the journal may use up at most. SystemKeepFree= and RuntimeKeepFree= control how much disk space systemd-journald shall leave free for other uses. systemd-journald will respect both limits and use the smaller of the two values.

The first pair defaults to 10% and the second to 15% of the size of the respective file system, but each value is capped to 4G.

[–] [email protected] 13 points 2 months ago

If anything I tend to have the opposite problem: whoops I forgot to set up logrotate for this log file I set up 6 months ago and now my disk is completely full. Never happens for stuff that goes to journald.

[–] [email protected] 4 points 2 months ago* (last edited 2 months ago) (1 children)

It can be, but the defaults are freaking stupid and often do not work.

[–] Starbuck 18 points 2 months ago (1 children)

Aren’t the defaults set by your distro?

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[–] [email protected] 5 points 2 months ago (2 children)

Still boggles my mind that systemd being terrible is still a debate. Like of all things, wouldn’t text logs make sense?

[–] [email protected] 5 points 2 months ago (2 children)

Wait… it doesn’t store them in plaintext?

[–] uranibaba 4 points 2 months ago (1 children)

Nope, you need journalctl to read.

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[–] [email protected] 4 points 2 months ago

Wouldn't compressed logs make even more sense (they way they're now)?

[–] [email protected] 16 points 2 months ago

This once happened to me on my pi-hole. It's an old netbook with 250 GB HDD. Pi-hole stopped working and I checked the netbook. There was a 242 GB log file. :)

[–] SuperIce 11 points 2 months ago

Systems/Journald keeps 4GB of logs stored by default.

[–] [email protected] 10 points 2 months ago (1 children)

Recently had the jellyfin log directory take up 200GB, checked the forums and saw someone with the same problem but 1TB instead.

[–] Agent641 16 points 2 months ago* (last edited 2 months ago)

2024-03-28 16:37:12:017 - Everythings fine

2024-03-28 16:37:12:016 - Everythings fine

2024-03-28 16:37:12:015 - Everythings fine

[–] [email protected] 10 points 2 months ago
[–] [email protected] 7 points 2 months ago* (last edited 2 months ago)

logrotate is a thing.

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

Windows isn't great by any means but I do like the way they have the Event Viewer layout sorted to my tastes.

[–] [email protected] 3 points 2 months ago

True that. Sure, I need to keep my non-professional home sysadmin skills sharp and enjoy getting good at these things, but I wouldn't mind a better GUI journal reader / configurator thing. KDE has a halfway decent log viewer.

It might also go a long way towards helping the less sysadmin-for-fun-inclined types troubleshoot.

Maybe there is one and I just haven't checked. XD

[–] [email protected] 6 points 2 months ago

I recently discovered the company I work for, has an S3 bucket with network flow logs of several TB. It contains all network activity if the past 8 years.

Not because we needed it. No, the lifecycle policy wasn't configured correctly.

[–] [email protected] 5 points 2 months ago

I couldn't tell for a solid minute if the title was telling me to clear the journal or not

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