Intermittent Connectivity Problem [was Re:linux problem]

[JM]

On Tuesday 13 December 2005 4:43 am, Alex Beamish wrote:
> On 12/12/05, Robert Brockway <rbrockway-wgAaPJgzrDxH4x6Dk/4f9A at public.gmane.org> wrote:
> > On Mon, 12 Dec 2005, Jerome Macaranas wrote:
> > > hi all,
> > >
> > >       I have a system that serves HTTP and PGSQL ( serves locally only
> >
> > contents for
> >
> > > dynamic HTTP conntents )... it runs on Redhat 9 with 2G memory..... for
> >
> > some
> >
> > > reason the box just suddenly became unavailable... the server is
> >
> > pingable..
> >
> > > but services running on it is unaccessible .. HTTP, SSH... Ive already
> > > checked the logs... but didn't saw anything unusual..
>
> In addition to all of the good things Rob mentioned, have you VACUUMed your
> Postgres database recently?
>
> I experienced a 'knee' of performance on one of my database servers
> recently, and did a VACUUM that took 45 minutes to complete. After that,
> performance was almost two orders of magnitude better. There used to be a
> daily VACUUM on that server but due to some other changes it was disabled.
> There is now a daily VACUUM on all of my database servers.
>

its automatic to me that if a box has PG.. small or big ..it will VACUUMed 
every day...


> And of course, when all else fails, check what the log files are saying. If
> you use Nagios to monitor the server (from another box, obviously) you
> should get some kind of warning that the system is degrading.
>
> Looks like you've got some fun investigative work ahead of you.
>
> Alex
>
> If the box becomes unavailable how are you getting in to checkout the
>
> > logs?  If it is after a reboot then the horse has bolted - you need to
> > capture important data right after the system has the problem.
> >
> > Can you checkout the console when this is happening?  If it is not easy
> > to get to the keyboard & monitor consider setting up a serial console -
> > this is great for capturing console output for later.  Also checkout
> > dmesg.
> >
> > Turn all the logs you can to debug.  This will add load to the server. 
> > If the box is in production watch the system load.
> >
> > How long does the system last before it suffers this problem?  Minutes,
> > days, weeks?
> >
> > Google for cross references to your hardware, kernel, filesystems, etc
> > and watch for others reporting similar problems.
> >
> > Also, it's better to be more specific with the title.  Some people may
> > not checkout the thread based on the title, or you may get the wrong
> > people doing so (ie, those without enough experience).  If you used a
> > subject line of something like "Intermittent Connectivity Problem" (which
> > I have) you may tend to draw in the right audience more easily.
> >
> > Cheers,
> >
> > Rob
> >
> > --
> > Robert Brockway B.Sc.           Phone:  +1-416-669-3073
> > Senior Technical Consultant     Email:  support-wgAaPJgzrDxH4x6Dk/4f9A at public.gmane.org
> > OpenTrend Solutions Ltd.        Web:    www.opentrend.net
> > We are open 24x365 for technical support.  Call us in a crisis.
> > --
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