ntp offset stays at about 19 minutes

claforce · 09-10-2014, 02:18 PM

Hello,
I'm trying to resolve an issue I have on one of our servers where the ntp offset is at 1113 second or about 19 minutes. Right now it is showing 2:32PM when it is really 2:14PM. The server has the same ntp.conf as other servers in the same subnet which are not having issues, and ntpd is setup in chkconfig and is running. This is a CentOS 5.8 server.

Code:

# ntpq -pn
     remote           refid      st t when poll reach   delay   offset  jitter
==============================================================================
*4.53.160.75     204.9.54.119     2 u   15   64  377    6.840  -111338   0.463
+69.164.204.77   66.228.59.187    3 u    3   64  377   21.044  -111338   0.302
+50.7.64.4       147.231.2.6      2 u   26   64  377   33.878  -111338   0.279
 127.127.1.0     .LOCL.          10 l    9   64  377    0.000    0.000   0.001

# ntpdate -b time.nist.gov
10 Sep 14:24:53 ntpdate[20451]: step time server 128.138.141.172 offset -1113.385469 sec

I've even tried to force a change, but the time will not upudate.

Code:

# ntpd -gq
ntpd: time set -1113.391540s

or

Code:

#sntp -r time.nist.gov
The time correction is -1113.401 +/- 0.000+0.026 seconds
Do you want to correct the time anyway? y

Here is my currently /etc/ntp.conf

Code:

# 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 0.rhel.pool.ntp.org
server 1.rhel.pool.ntp.org
server 2.rhel.pool.ntp.org

#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

Please let me know if you can offer any assistance.
Thanks,

Chris.

keefaz · 09-10-2014, 02:45 PM

Offset is too big to be ajusted by ntpd.

try:

Code:

/usr/sbin/ntpdate 0.rhel.pool.ntp.org

Then ntpd should work

[edit]
Sorry, did not read carefully enough, you already tried that (even without -b ?) :/

Maybe you have to stop ntpd service before running ntpdate, then restart ntpd

metaschima · 09-10-2014, 03:11 PM

Commenting this section out will help prevent future large time offsets:

Code:

# 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

Otherwise you have to use 'ntpdate' or 'ntpd -q' to set it if there is a large offset.

claforce · 09-10-2014, 04:02 PM

metaschima,
I commented out this section and ran "ntpd -q", but it does not update my time.

Code:

# ntpd -gq
ntpd: time set -1113.379110s

Code:

# ntpq -p
     remote           refid      st t when poll reach   delay   offset  jitter
==============================================================================
 4.53.160.75     .STEP.          16 u    -   64    0    0.000    0.000   0.000
*time1.scl3.mozi .GPS.            1 u   23   64  377   55.966  -111337   0.337
 triangle.kansas .STEP.          16 u    -   64    0    0.000    0.000   0.000

Thanks,

Chris.

keefaz · 09-11-2014, 09:09 AM

Did you try to stop ntpd, update time, then start ntpd ?

claforce · 09-11-2014, 09:53 AM

keefaz,
Yes I did stop ntpd before I tried to update the time and then I restarted it when complete.

Thanks,

Chris.

metaschima · 09-11-2014, 10:38 AM

Can you try changing the time manually using date and hwclock ?

claforce · 09-11-2014, 11:04 AM

It appears I cannot set the time manually either. Is this an issue with hwclock?

Code:

#hwclock --show
Cannot access the Hardware Clock via any known method.

# date -s "11 SEP 2014 10:49:00"
Thu Sep 11 10:49:00 CDT 2014

# date
Thu Sep 11 11:07:34 CDT 2014

metaschima · 09-11-2014, 12:10 PM

Are you running a custom kernel ? Make sure the RTC is enabled in the kernel, otherwise you cannot set the time from the OS, only from BIOS.

keefaz · 09-11-2014, 12:20 PM

yup, also rtc error should show up in dmesg

claforce · 09-11-2014, 03:08 PM

So it appears that RTC must not have been built into the kernel:

Code:

# dmesg | grep rtc
rtc: IRQ 8 is not free.

Looks like it's a xen kernel

Code:

$ uname -a
Linux 2.6.18-194.11.4.el5xen #1 SMP Fri Sep 17 05:17