[logs] Logging oddity from FreeBSD Oct 26 2007 12:46AM
Tina Bird (tbird precision-guesswork com) (1 replies)
Re: [logs] Logging oddity from FreeBSD Oct 26 2007 02:15AM
Mordechai T. Abzug (morty frakir org) (1 replies)
RE: [logs] Logging oddity from FreeBSD Oct 26 2007 02:19AM
Tina Bird (tbird precision-guesswork com) (1 replies)

> > Jun 13 00:57:57 <hostname> kernel:
> >
> > Jun 13 00:57:57 <hostname> named[45636]: transfer of
> 'example.com/IN' from
> > xyz.xyz.xyz.xyz#53: failed to connect: timed out

> I have seen this something similar elsewhere with a different vendor's
> *nix + modified kernel (hi, Marcus) + syslogd. It tended to happen
> when the system was busy and logging a *lot* of messages at the kernel
> level. On some *nix systems, logging from kernel space to user space
> happens by way of a circular buffer. I think what happens is that the
> kernel is producing logs faster than userspace can actually read them,
> so syslogd/klogd gets partial messages at the wraparound point.

Yeah, that's exactly the scenario I was imagining...I'm sure there was a
list discussion about it at some point around here.

> You should be able to sim/stim this by setting up a system with a
> firewall that does a lot of logging from kernel space, no rate
> limiting for the logging, loading up the system with some CPU-hogging
> and IO-hogging processes, and throwing a wide variety of bad traffic
> at it really fast, for a while. The kernel log buffer will fill up,
> and then syslogd will start reading partial lines.
> Oh, and you've made certain that there aren't vt100 or ANSI escapes
> that are playing cursor games, right?

It's archival data. I am not sufficiently bothered right this very moment to
explore it any more deeply, but at least I've had someone validate my
speculation that it was due to poorly behaved buffering.

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[ reply ]
[logs] Feedback Needed: Large Scale Syslog Management Oct 29 2007 07:04PM
Clayton Dukes (cdukes) (cdukes cisco com)


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