[CentOS-de] Systemzeit galoppiert davon trotz ntpd und korrekten Zeitservern

[Frank Thommen]

Hallo zusammen,

auf einer (einzigen) Machine laeuft uns - wortwoertlich - die Zeit 
davon.  Seit der letzten harten Zeitsynchronisation (`ntpdate 
<timeserver>` bei angehaltenem ntpd) vor ca 1.5 Stunden, ist die Uhr 
schon ueber 15 Minuten zu schnell gelaufen.  Die Zeitdifferenz wird 
imemr groesser je laenger der Rechner laeuft.  Seit wann das PRoblem 
existiert laesst sich im Moment nicht sagen.  Alle Rechner haben bei uns 
denselben - neuesten - Patchlevel von CentOS 5.5 und dasselbe /etc/ntp.conf:

----------------------------------
# Permit time synchronization with our time source, but do not
# permit the source to query or modify the service on this system.
restrict default kod nomodify notrap nopeer noquery
restrict -6 default kod nomodify notrap nopeer noquery

# Permit all access over the loopback interface.  This could
# be tightened as well, but to do so would effect some of
# the administrative functions.
restrict 127.0.0.1
restrict -6 ::1

# Hosts on local network are less restricted.
#restrict 192.168.1.0 mask 255.255.255.0 nomodify notrap

# Use public servers from the pool.ntp.org project.
# Please consider joining the pool (http://www.pool.ntp.org/join.html).
server timeserver-1.embl.de
server timeserver-2.embl.de
server timeserver-3.embl.de

#broadcast 192.168.1.255 key 42		# broadcast server
#broadcastclient			# broadcast client
#broadcast 224.0.1.1 key 42		# multicast server
#multicastclient 224.0.1.1		# multicast client
#manycastserver 239.255.254.254		# manycast server
#manycastclient 239.255.254.254 key 42	# manycast client

# Undisciplined Local Clock. This is a fake driver intended for backup
# and when no outside source of synchronized time is available.
server	127.127.1.0	# local clock
fudge	127.127.1.0 stratum 10	

# Drift file.  Put this in a directory which the daemon can write to.
# No symbolic links allowed, either, since the daemon updates the file
# by creating a temporary in the same directory and then rename()'ing
# it to the file.
driftfile /var/lib/ntp/drift

# Key file containing the keys and key identifiers used when operating
# with symmetric key cryptography.
keys /etc/ntp/keys

# Specify the key identifiers which are trusted.
#trustedkey 4 8 42

# Specify the key identifier to use with the ntpdc utility.
#requestkey 8

# Specify the key identifier to use with the ntpq utility.
#controlkey 8
[root at shelley ~]#
----------------------------------


Aus irgendeinem Grund synchronisiert dieser Host aber mit der lokalen 
Uhr (?) statt mit unseren Zeitservern:


[schlechter host]# ntpstat
synchronised to local net at stratum 11
    time correct to within 11 ms
    polling server every 1024 s
[schlechter host]#  ntpq -p
      remote           refid      st t when poll reach   delay   offset 
  jitter
==============================================================================
  pbs-master2.emb 130.149.17.21    2 u  893 1024  377    0.292  -732094 
123952.
  dns2.embl.de    131.188.3.220    2 u  832 1024  377    0.757  -615821 
123543.
*LOCAL(0)        .LOCL.          10 l   26   64  377    0.000    0.000 
  0.001
[schlechter host]#


statt


[guter host]$ ntpstat
synchronised to NTP server (192.54.41.96) at stratum 3
    time correct to within 81 ms
    polling server every 1024 s
[guter host]$ /usr/sbin/ntpq -p
      remote           refid      st t when poll reach   delay   offset 
  jitter
==============================================================================
  10.1.104.79     130.149.17.21    2 u  36d 1024    0    0.244    0.129 
   0.000
*dns2.embl.de    131.188.3.220    2 u  785 1024  377    0.656   -1.405 
  0.772
  LOCAL(0)        .LOCL.          10 l   31   64  377    0.000    0.000 
   0.001
[guter host]$


Irgendeine Idee woran das liegen koennte oder wie man dem Problem auf 
die Schliche kommen koennte?


Gruss und Danke

    frank


-- 
Frank Thommen - Structures IT Management and Support - EMBL Heidelberg
frank.thommen at embl-heidelberg.de - +49 6221 387 8353