[nSLUG] No CPU use stat from ps running bind in chroot

D G Teed donald.teed at gmail.com
Tue Jul 25 12:29:03 ADT 2006


I suspect the issue isn't on the ps side but in the named side.
Running strace on ps shows it is reading within /proc as expected.
As I'm doing ps from the main OS, it has no issues accessing that.

This isn't a full chroot jail, but simply using bind's own chroot
mechanism.  Therefore, there is a very minimal environment
there - no shell, libs, etc.  If bind couldn't find the /proc
slot for its process before, it should be able to now by the
mount I created.

Perhaps there is some problem between certain kernels and
chroot'ed named?  ps is just grabbing the stuff under /proc/$PID
and making it pretty to read, AFAIK.

--Donald

On 7/25/06, Crawford, Andrew (IT) <Andrew.Crawford at morganstanley.com> wrote:
> Try stracing the ps in the chroot environment and note any file accesses. Other than that, I wonder if there's a difference in your chrooted execution environment in terms of libraries etc. In any case comparing all file opens in strace in regular vs chroot should shed light.
>
> Cheers,
>
> Andrew Crawford
>
> > -----Original Message-----
> > From: nslug-bounces at nslug.ns.ca [mailto:nslug-bounces at nslug.ns.ca] On
> > Behalf Of D G Teed
> > Sent: Tuesday, July 25, 2006 10:11
> > To: nslug
> > Subject: [nSLUG] No CPU use stat from ps running bind in chroot
> >
> > Hi,
> >
> > Here is a scenario...
> > Two servers: both Debian 3.1 stable.
> >
> > One runs with -t /var/lib/named while the other doesn't.
> > Both work properly.
> >
> > The chrooted bind will show 0:00 for processing time from ps -aux , while
> > the non-chrooted case will show some processing time has elapsed.
> > (The chrooted case is far more busy, as well, so it isn't simply a case
> > of an idle service.)
> >
> > I checked the bind chroot howto and don't see anything I've missed.
> > googling hasn't shown anything related to it thus far.
> >
> > My feeling is that I'm missing something in named's dev
> > (I've got null, random and log) or similar.
> >
> > --Donald
> >
> >
> >
> > _______________________________________________
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> > nSLUG at nslug.ns.ca
> > http://nslug.ns.ca/cgi-bin/mailman/listinfo/nslug
> >
> >
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