[CentOS] CentOs 5.6 and Time Sync

[Cal Webster]

On Wed, 2011-04-13 at 16:22 -0400, Mailing List wrote:
> On 4/13/2011 3:35 PM, Cal Webster wrote:
> >
> > I'm running the same kernel and ntp versions and I'm having no problems
> > at all on ntp servers or clients.
> >
> > If my previous suggestions didn't help maybe you could share contents of
> > the following files and output of some commands so the list can see what
> > you've got.
> >
> > /etc/ntp.conf
> > /etc/ntp/ntpservers
> > /etc/ntp/step-tickers
> > /var/lib/ntp/drift
> >
> >
> > grep ntpd /var/log/messages*
> > (please remove repeated messages for clarity)
> >
> > Most recent entries in /var/log/ntpd.log
> >
> > SELinux could also be playing a role.
> >
> > Are you running SELinux enabled, permissive, or disabled?
> > What mode was it running before it stopped working?
> > Are there any possibly related "avc" messages in /var/log/messages
> > or /var/audit/audit.log?
> >
> > ./Cal
> >
>   /etc/ntp;
> 
> restrict default kod nomodify notrap nopeer noquery
> restrict -6 default kod nomodify notrap nopeer noquery
> restrict 127.0.0.1
> restrict -6 ::1
> server 0.centos.pool.ntp.org
> server 1.centos.pool.ntp.org
> server 2.centos.pool.ntp.org
> server  127.127.1.0     # local clock
> fudge   127.127.1.0 stratum 10
> driftfile /var/lib/ntp/drift
> keys /etc/ntp/keys
> 
> There is no /etc/ntp/ntpservers
> 
> /etc/ntp/step-tickers is an empty file.
> 
> /var/lib/ntp/drift;
>    -65.219
> 
> I have no /var/log/ntpd.log
> 
> /varlog/messages;  This is the log using stock updated kernel.
> 
> Apr 12 03:32:35 Server ntpd[2797]: synchronized to LOCAL(0), stratum 10
> Apr 12 03:33:36 Server ntpd[2797]: synchronized to 173.9.142.98, stratum 2
> Apr 12 15:51:56 Server ntpd[2797]: time reset +43208.248852 s
> Apr 12 15:51:56 Server ntpd[2797]: kernel time sync enabled 0001
> Apr 12 15:56:03 Server ntpd[2797]: synchronized to LOCAL(0), stratum 10
> Apr 12 15:56:26 Server ntpd[2797]: synchronized to 169.229.70.183, stratum 3
> Apr 12 16:00:22 Server ntpd[2797]: synchronized to 173.9.142.98, stratum 2
> Apr 12 16:16:59 Server ntpd[2797]: synchronized to 169.229.70.183, stratum 2
> Apr 12 16:16:57 Server ntpd[2797]: time reset -1.830305 s
> Apr 12 16:20:27 Server ntpd[2797]: synchronized to LOCAL(0), stratum 10
> Apr 12 16:22:35 Server ntpd[2797]: synchronized to 169.229.70.183, stratum 2
> Apr 12 16:28:01 Server ntpd[2797]: synchronized to 173.9.142.98, stratum 2
> Apr 12 16:32:29 Server ntpd[2797]: synchronized to 169.229.70.183, stratum 3
> Apr 12 16:36:36 Server ntpd[2797]: synchronized to 173.9.142.98, stratum 2
> Apr 12 16:40:05 Server ntpd[2797]: synchronized to 169.229.70.183, stratum 3
> Apr 12 16:41:57 Server ntpd[2797]: synchronized to LOCAL(0), stratum 10
> Apr 12 16:42:09 Server ntpd[2797]: synchronized to 173.9.142.98, stratum 2
> Apr 12 16:47:28 Server ntpd[2797]: synchronized to LOCAL(0), stratum 10
> Apr 12 16:48:28 Server ntpd[2797]: synchronized to 169.229.70.183, stratum 3
> Apr 12 16:51:44 Server ntpd[2797]: synchronized to 173.9.142.98, stratum 2
> Apr 12 16:53:52 Server ntpd[2797]: synchronized to 173.193.227.67, stratum 4
> Apr 12 16:58:06 Server ntpd[2797]: synchronized to 169.229.70.183, stratum 3
> Apr 12 17:00:18 Server ntpd[2797]: synchronized to LOCAL(0), stratum 10
> Apr 12 17:04:31 Server ntpd[2797]: synchronized to 169.229.70.183, stratum 3
> Apr 12 17:06:44 Server ntpd[2797]: synchronized to LOCAL(0), stratum 10
> Apr 12 19:54:46 Server ntpd[2797]: ntpd exiting on signal 15
> Apr 13 03:01:24 Server ntpd[2409]: ntpd 4.2.2p1 at 1.1570-o Sat Dec 19 
> 00:56:13 UTC 2009 (1)
> Apr 13 03:01:24 Server ntpd[2410]: precision = 1.000 usec
> Apr 13 03:01:24 Server ntpd[2410]: Listening on interface wildcard, 
> 0.0.0.0#123 Disabled
> Apr 13 03:01:24 Server ntpd[2410]: Listening on interface wildcard, 
> ::#123 Disabled
> Apr 13 03:01:24 Server ntpd[2410]: Listening on interface lo, ::1#123 
> Enabled
> Apr 13 03:01:24 Server ntpd[2410]: Listening on interface eth0, 
> fe80::218:8bff:fe80:67db#123 Enabled
> Apr 13 03:01:24 Server ntpd[2410]: Listening on interface lo, 
> 127.0.0.1#123 Enabled
> Apr 13 03:01:24 Server ntpd[2410]: Listening on interface eth0, 
> 192.168.2.1#123 Enabled
> Apr 13 03:01:24 Server ntpd[2410]: kernel time sync status 0040
> Apr 13 03:01:30 Server ntpd[2410]: frequency initialized 0.000 PPM from 
> /var/lib/ntp/drift
> Apr 13 07:04:44 Server ntpd[2410]: synchronized to LOCAL(0), stratum 10
> Apr 13 07:04:44 Server ntpd[2410]: kernel time sync enabled 0001
> Apr 13 07:11:09 Server ntpd[2410]: synchronized to 208.75.88.4, stratum 2
> Apr 13 07:17:34 Server ntpd[2410]: synchronized to 64.6.144.6, stratum 2
> Apr 13 07:42:59 Server ntpd[2410]: time reset -27.586767 s
> Apr 13 07:46:35 Server ntpd[2410]: synchronized to LOCAL(0), stratum 10
> Apr 13 07:47:38 Server ntpd[2410]: synchronized to 199.249.224.123, 
> stratum 2
> Apr 13 07:51:53 Server ntpd[2410]: synchronized to 64.6.144.6, stratum 2
> Apr 13 09:27:19 Server ntpd[2410]: ntpd exiting on signal 15
> Apr 13 09:27:19 Server ntpd[6743]: ntpd 4.2.2p1 at 1.1570-o Sat Dec 19 
> 00:56:13 UTC 2009 (1)
> 
>    Selinux is disabled, and just a note also. This is a stock install of 
> of ntp. I never had to do any fudging with it cause it just worked up 
> until the update.
> 
>   I also have no /var/log/audit/audit.log.

I don't have any CentOS machines with direct Internet connections but I
compared your config and logs to my internal machines and an external
FC12 box.

Your time resets are wildly fulctuating between +720 min (12 hours) and
-2 seconds over the course of only one hour, according to the log. I
have no way of knowing how much actual time had elapsed but the ntp
daemon decided the step threshold had been exceeded and reset the time
according to its time source.

If you are indeed getting good time from the ntp pool, then either your
local system clock is malfunctioning or the kernel driver is getting bad
clock readings. Even network outages would not produce such a large
range of resets in such a short period.

I'd be interested to see the output of:

ntpq -c pe -c as

You might try commenting out the local clock entries in /etc/ntp.conf
and see if that changes your symptoms.

#server  127.127.1.0     # local clock
#fudge   127.127.1.0 stratum 10

./Cal