[CentOS] timekeeping on VMware guests

Akemi Yagi amyagi at gmail.com
Thu Oct 15 23:05:24 UTC 2009


On Wed, Oct 14, 2009 at 10:04 AM, Ray Van Dolson <rayvd at bludgeon.org> wrote:
> On Wed, Oct 14, 2009 at 10:55:40AM -0500, Carlos Santana wrote:

>> 1. Kernel options added as:
>> divider=10
>> clocksource=acpi_pm
>>
>> 2. ntp.conf file was modified as per wiki instructions as follows:
>> (add to the top of the file)
>> # modification as per http://kb.vmware.com/kb/1006427
>> # The configuration directive tinker panic 0 instructs NTP not to give up
>> # if it sees a large jump in time and must be at the top of the ntp.conf file.
>> tinker panic 0
>> # end of mod
>>
>> (comment out 2 lines as below)
>> # modification as per http://kb.vmware.com/kb/1006427
>> # It is also important not to use the local clock as a time source,
>> # often referred to as the Undisciplined Local Clock. NTP has a
>> # tendency to fall back to this in preference to the remote servers
>> # The following 2 lines commented out.
>>
>> # when there is a large amount of time drift.
>> # server        127.127.1.0     # local clock
>> # fudge 127.127.1.0 stratum 10
>>
>> 3. Create /etc/ntp/step-tickers and add these lines:
>> 0.centos.pool.ntp.org
>> 1.centos.pool.ntp.org
>> ----------------------
>>
>> Any missing pointers..?
>
> Looks good to me.  The only issue might be if you have a firewall
> blocking access to the given NTP servers.
>
> What kind of symptoms are you seeing after doin the above, rebooting,
> sync'ing the time, then leaving ntpd doing it's thing?
>
> Does the clock start going too fast?  Too slow?  Do you see any errors
> in dmesg or /var/log/messages?

Indeed, that is a good question.  In /var/log/messages, do you see a
line similar to:

<date time> <host>  ntpd[6569]: synchronized to xxx.xxx.xxx.xxx

Akemi


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