FAQ Search Today's Posts Mark Forums Read
» Video Reviews

» Linux Archive

Linux-archive is a website aiming to archive linux email lists and to make them easily accessible for linux users/developers.


» Sponsor

» Partners

» Sponsor

Go Back   Linux Archive > CentOS > CentOS

 
 
LinkBack Thread Tools
 
Old 04-16-2008, 10:00 PM
"Michael A. Peters"
 
Default No Network = slow ??

I lost my internet connection earlier today.
My home network was still up - it's just the router couldn't get an IP
from the cable modem.


During that period, my CentOS 5.1 install was extremely slow (2.6 GHz
Athlon w/ 2GB ram) at starting non network applications - such as
solitare and gnome terminal. It would pause for several seconds before
finally starting them.


The machine does run bind as a caching nameserver - as I've found that
to be more reliable than using my ISPs nameserver, so I'm guessing the
slowdown was with bind not being able to resolve anything.


Is there anything I can do to prevent the slow application launching in
the event of lost network in the future?

_______________________________________________
CentOS mailing list
CentOS@centos.org
http://lists.centos.org/mailman/listinfo/centos
 
Old 04-16-2008, 10:05 PM
Milton Calnek
 
Default No Network = slow ??

Startup wireshark... find out what those "non-network" apps are doing on the network.

What's your /etc/hosts file look like?

Michael A. Peters wrote:

I lost my internet connection earlier today.
My home network was still up - it's just the router couldn't get an IP
from the cable modem.


During that period, my CentOS 5.1 install was extremely slow (2.6 GHz
Athlon w/ 2GB ram) at starting non network applications - such as
solitare and gnome terminal. It would pause for several seconds before
finally starting them.


The machine does run bind as a caching nameserver - as I've found that
to be more reliable than using my ISPs nameserver, so I'm guessing the
slowdown was with bind not being able to resolve anything.


Is there anything I can do to prevent the slow application launching in
the event of lost network in the future?

_______________________________________________
CentOS mailing list
CentOS@centos.org
http://lists.centos.org/mailman/listinfo/centos



--
Milton Calnek BSc, A/Slt(Ret.)
milton@calnek.com
306-717-8737


--
This message has been scanned for viruses and
dangerous content by MailScanner, and is
believed to be clean.

_______________________________________________
CentOS mailing list
CentOS@centos.org
http://lists.centos.org/mailman/listinfo/centos
 
Old 04-17-2008, 03:39 AM
"Bart Schaefer"
 
Default No Network = slow ??

On Wed, Apr 16, 2008 at 3:00 PM, Michael A. Peters <mpeters@mac.com> wrote:
> I lost my internet connection earlier today.
>
> During that period, my CentOS 5.1 install was extremely slow (2.6 GHz
> Athlon w/ 2GB ram) at starting non network applications - such as solitare
> and gnome terminal. It would pause for several seconds before finally
> starting them.

There's a couple of threads about this from May 2007 or thereabouts
that you should be able to find in the list archives. (I know because
I started those threads.) The short answer seems to be that Xorg gets
annoyed if it can't resolve the local IP address to a hostname, and it
attempts to do this any time any application connects to the X server.
Other (non-X) apps will cause similar issues if they attempt DNS
operations for any reason while the network is down.

You can fix *most* of this by making sure that there are entries in
/etc/hosts for 127.0.0.1, etc., but I was never able to get the
problem to entirely go away in all circumstances.
_______________________________________________
CentOS mailing list
CentOS@centos.org
http://lists.centos.org/mailman/listinfo/centos
 
Old 04-17-2008, 03:25 PM
"Michael A. Peters"
 
Default No Network = slow ??

Bart Schaefer wrote:



You can fix *most* of this by making sure that there are entries in
/etc/hosts for 127.0.0.1, etc., but I was never able to get the
problem to entirely go away in all circumstances.


OK - my /etc/hosts file contained the following EXCEPT for the last line
(fqdn) added this morning:


# Do not remove the following line, or various programs
# that require network functionality will fail.
127.0.0.1 localhost.localdomain localhost athens
::1 localhost6.localdomain6 localhost6
192.168.15.2 jerusalem.mpeters.local jerusalem
192.168.15.5 laserjet.mpeters.local laserjet
192.168.15.23 athens.mpeters.local

Hopefully it was lack of fqdn in /etc/hosts - though that would be
puzzling, as I don't run any dns that defines that host name, so why it
would cause slowdown when I can't reach the outside world because of
lack of fqdn that it didn't have anyway is puzzling.


Another possibility - I have the gnome weather applet running on the
panel, it could not update obviously as it could not get outside local
lan, I don't know if that would have triggered gnome/x11 slowness or not.

_______________________________________________
CentOS mailing list
CentOS@centos.org
http://lists.centos.org/mailman/listinfo/centos
 
Old 04-17-2008, 06:08 PM
Florin Andrei
 
Default No Network = slow ??

Michael A. Peters wrote:

I lost my internet connection earlier today.
My home network was still up - it's just the router couldn't get an IP
from the cable modem.


During that period, my CentOS 5.1 install was extremely slow (2.6 GHz
Athlon w/ 2GB ram) at starting non network applications - such as
solitare and gnome terminal. It would pause for several seconds before
finally starting them.


I've seen this issue showing up every once in a while for many years. It
is _always_ due to DNS.


Just make sure that, even when offline, the system can still resolve
things such as localhost, its own IP address, stuff like that. You can
definitely find, always, what the problem is, by running a sniffer, a
tracer/debugger, etc. It's just that it's time-consuming to troubleshoot
due to the very nature of the problem - it takes a long time to elicit
any kind of response from the system.


Make sure DNS is properly configured, test beforehand by pulling the
network cable (so that network failure will not catch you unawares) and
everything should then be fine.


I've been hit by this issue so many times that now I'm really obsessed
with correct network and DNS settings. In the long run it's the good
kind of obsession.


Tip: if the system is multihomed, and the DNS resolution for the
external interface depends on a remote DNS server, do not configure the
external interface as primary (do not assign the system hostname the
same as the hostname for that interface).
Instead, assign it the hostname corresponding to the internal interface,
which is always under your control, and for whom the DNS never goes
offline (since it's local). Then just juggle with Apache, Postfix, etc.
settings if these services need to run primarily on the external interface.
I can't explain this better in a short paragraph, but I'm sure there's
plenty of people who've been there and arrived to the same conclusion:
Anything remote is unreliable, so don't depend on it for local settings.


--
Florin Andrei

http://florin.myip.org/
_______________________________________________
CentOS mailing list
CentOS@centos.org
http://lists.centos.org/mailman/listinfo/centos
 

Thread Tools




All times are GMT. The time now is 05:17 PM.

VBulletin, Copyright ©2000 - 2014, Jelsoft Enterprises Ltd.
Content Relevant URLs by vBSEO ©2007, Crawlability, Inc.
Copyright 2007 - 2008, www.linux-archive.org