[CentOS] Systemd debug logging turned on in CentOS 7

Tue Feb 28 16:55:32 UTC 2017
Brian Mathis <brian.mathis+centos at betteradmin.com>

On Tue, Feb 28, 2017 at 10:49 AM, Valeri Galtsev <galtsev at kicp.uchicago.edu>
wrote:

>
> On Tue, February 28, 2017 9:22 am, Rob DeSanno wrote:
> > Last time I saw it, I had just upgraded my CentOS 7 box with the
> > 3.10.0-514 kernel and it rebooted already configured into debug mode.
> Not
> > sure if this is a “feature† of the newer kernels or not but glad to
> > see that i’m not the only one who had noticed this.
> >
> > # awk -F\' '$1=="menuentry " {print i++ " : " $2}' /etc/grub2.cfg
> > 0 : CentOS Linux (3.10.0-514.6.2.el7.x86_64) 7 (Core)
> > 1 : CentOS Linux (3.10.0-514.6.2.el7.x86_64) 7 (Core) with debugging
> > 2 : CentOS Linux (0-rescue-7b37bcbe36eb420fb6426976c41b0aaf) 7 (Core)
> > 3 : CentOS Linux (0-rescue-7b37bcbe36eb420fb6426976c41b0aaf) 7 (Core)
> with
> > debugging
>
> I am not certain if there is real harm to have kernel with all debug stuff
> running on production machines. Probably no harm security wise, the only
> unpleasant stuff is: you really would prefer to run as slim kernel as
> possible on production systems. If I'm wrong about "no harm", somebody
> chime in, I then will be really eager to address it on my boxes.
>
> Valeri
>
>

Main issue I've seen is that logs grow by an order of magnitude larger than
when it's off, due to systemd being systemd and now running in debug mode.
Other than disk space, it would affect any central logging system you have
with lots of unnecessary traffic, and would also add a lot of IO, amplified
if you have many machines running on a VM host.

~ Brian Mathis
@orev