Re: ntp issue on linux server, time goes ahead (888 Views)
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Super Advisor
Super Advisor
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Posts: 211
Registered: ‎03-23-2008
Message 1 of 13 (888 Views)

ntp issue on linux server, time goes ahead

Hi All,

I am using a BL 460c blade for a linux (rhel 5.3 64bit)host and an oracle dbase runs in. I am facing an issue with the timing now. If I am restarting the ntpd service, time sync with the server but slowly it goes ahead upto 10 min in two weeks which makes my database screwed. All other server connected to my time server is working well. I have given few outputs below. Please help me in this.

[root@prodsrvr log]# dig timesrv.dc

; <<>> DiG 9.3.4-P1 <<>> timesrv.dc
;; global options: printcmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NXDOMAIN, id: 20578
;; flags: qr rd ra; QUERY: 1, ANSWER: 0, AUTHORITY: 1, ADDITIONAL: 0

;; QUESTION SECTION:
;timesrv.dc. IN A

;; AUTHORITY SECTION:
. 10759 IN SOA a.root-servers.net. nstld.verisign-grs.com. 2010072001 1800 900 604800 859

;; Query time: 0 msec
;; SERVER: 192.168.0.20#53(192.168.0.20)
;; WHEN: Tue Jul 20 23:38:40 2010
;; MSG SIZE rcvd: 108


[root@prodsrvr log]# nslookup timesrv.dc.com
Server: 192.168.0.20
Address: 192.168.0.20#53

Name: timesrv.dc.com
Address: 192.168.0.20


[root@prodsrvr log]#
[root@prodsrvr log]# ntpq -p
remote refid st t when poll reach delay offset jitter
==============================================================================
timesrv.dc .LOCL. 1 u 20 64 377 0.248 -268.90 136.550
[root@prodsrvr log]#
Honored Contributor
Tim Nelson
Posts: 3,727
Registered: ‎06-01-2000
Message 2 of 13 (888 Views)

Re: ntp issue on linux server, time goes ahead

Is ntpd running ?

service ntpd status



Super Advisor
Super Advisor
AVV
Posts: 211
Registered: ‎03-23-2008
Message 3 of 13 (888 Views)

Re: ntp issue on linux server, time goes ahead

Hi,

ntpd is running. I have confirmed that first.

#service ntpd status
ntpd (pid 11107) is running...
Respected Contributor
Wilfred Chau_1
Posts: 404
Registered: ‎12-13-2000
Message 4 of 13 (888 Views)

Re: ntp issue on linux server, time goes ahead

How come timesrv.dc.com resolves to an 192.168.0.0 IP ? Does it connect to an external NTP source?

Try change your ntp to use a public NTP server nearest to your machine from this url:
http://support.ntp.org/bin/view/Servers/NTPPoolServers


Honored Contributor
Matti_Kurkela
Posts: 6,271
Registered: ‎12-02-2001
Message 5 of 13 (888 Views)

Re: ntp issue on linux server, time goes ahead

If there is no asterisk (*) in the first column in the "ntpq -p" output, the ntpd service has _not_ synchronized with a NTP server, so it cannot correct the system clock effectively.

Your offset value (estimated difference of the time value between your ntpd and the NTP server) is -268.90 ms: this is currently too much. For successful synchronization, the offset would have to be smaller than 128 ms (positive or negative).

The root cause for non-synchronization is probably the high jitter: if the round-trip delay in the communication between ntpd and the NTP server has more than about 100 ms of jitter, ntpd will drop out of sync so often that it will be almost useless. (The NTP documentation says the jitter value is an exponentially weighted root-mean-square average deviation from the average delay.)

In practice, the large jitter value means that the travel time of the NTP time message from the NTP server to your ntpd is not predictable enough. Jitter usually becomes high when you're trying to synchronize time over a very congested/overloaded network connection.

If you have other servers connected to the same switch as this BL460c blade, the congested connection might be the one between the blade and the switch. If possible, you should take a look at the switch port statistics and find out how busy the blade's network interfaces are.

If you have only one active network interface, consider setting up bonding to get more network bandwidth to your blade.

MK
MK
Super Advisor
bullz
Posts: 209
Registered: ‎08-11-2009
Message 6 of 13 (888 Views)

Re: ntp issue on linux server, time goes ahead

I had the similar problem.

It's a VM?

If so, please login to your VC console and check the time at your VC console

It might help you.
Super Advisor
Super Advisor
AVV
Posts: 211
Registered: ‎03-23-2008
Message 7 of 13 (888 Views)

Re: ntp issue on linux server, time goes ahead

This is not a VM but a physical blade server BL 460c
Trusted Contributor
John Guster
Posts: 506
Registered: ‎03-16-2006
Message 8 of 13 (888 Views)

Re: ntp issue on linux server, time goes ahead

what is the content of the file /etc/ntp.conf?
Frequent Advisor
Ricky_HK
Posts: 27
Registered: ‎02-21-2008
Message 9 of 13 (888 Views)

Re: ntp issue on linux server, time goes ahead

For me, I don't use NTP service.
Just add /usr/sbin/ntpdate -s to root crontab, let cron run it one or more times everyday... simple and easy.
Honored Contributor
Elmar P. Kolkman
Posts: 1,179
Registered: ‎10-16-2003
Message 10 of 13 (888 Views)

Re: ntp issue on linux server, time goes ahead

You should try to setup a better NTP network. Have multiple servers (peers) use their clocks to provide the time to the rest of the network and let all other machines on your network use multiple NTP servers for time synchronisation, so that the best server is chosen.

Also have you own local clock in the ntp.conf (server 127.127.1.1).
Every problem has at least one solution. Only some solutions are harder to find.
Honored Contributor
Elmar P. Kolkman
Posts: 1,179
Registered: ‎10-16-2003
Message 11 of 13 (888 Views)

Re: ntp issue on linux server, time goes ahead

One other thing: make sure a correct Proliant Support Pack is installed... It is needed to set the time in the hardware clock.
Every problem has at least one solution. Only some solutions are harder to find.
Honored Contributor
Bill McNAMARA_1
Posts: 3,866
Registered: ‎11-14-2000
Message 12 of 13 (888 Views)

Re: ntp issue on linux server, time goes ahead

check the ntpd -q output and the sysconfig options..


for reference:


[root@oclab50 ~]# ntpq -p
remote refid st t when poll reach delay offset jitter
==============================================================================
153.16.4.137 .INIT. 16 u - 64 0 0.000 0.000 0.000
ns1.your-site.c .INIT. 16 u - 64 0 0.000 0.000 0.000
c-68-51-42-35.h .INIT. 16 u - 64 0 0.000 0.000 0.002
LOCAL(0) .LOCL. 10 l - 64 0 0.000 0.000 0.002
[root@oclab50 ~]# cat /etc/sysconfig/ntpd
# Drop root to id 'ntp:ntp' by default.
OPTIONS="-x -u ntp:ntp -p /var/run/ntpd.pid"

# Set to 'yes' to sync hw clock after successful ntpdate
SYNC_HWCLOCK=no

# Additional options for ntpdate
NTPDATE_OPTIONS=""

It works for me (tm)
Super Advisor
Super Advisor
AVV
Posts: 211
Registered: ‎03-23-2008
Message 13 of 13 (888 Views)

Re: ntp issue on linux server, time goes ahead

Thanks
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