[Cialug] xen and ntp on centos

Barry Von Ahsen barry at vonahsen.com
Tue Aug 16 09:23:06 CDT 2011


the solution, it seems, is to pass a bunch of parameters at boot time

divider=10 clocksource=acpi_pm lpj=n

there's a RH KB article hidden in their support area.  since adding 
those and rebooting, the guests seem fine a day later

-barry


On 8/5/2011 1:44 PM, Barry Von Ahsen wrote:
> domU was just +1:10, so it's gained 30 minutes since yesterday :(
>
>
> I'm going to set this up on RHEL-proper servers then annoy their
> support. even on a RHEL domU, there is no /proc/sys/xen
>
>
> -barry
>
>
> On 8/4/2011 3:33 PM, Barry Von Ahsen wrote:
>> yes, this again :)
>>
>> every document in the world says run ntpd on dom0, and domU will
>> automatically update, except it doesn't on centos. in the last 24 hours
>> (when I manually fixed it), domU is nearly 40 minutes fast.
>>
>> several sources said to check /proc/sys/xen/independent_wallclock on the
>> guest, but I don't have a /proc/sys/xen there, am I missing a package?
>>
>>
>> simul-date:
>> [barry at xen ~]# date
>> Thu Aug 4 15:25:45 CDT 2011
>> [barry at domU ~]$ date
>> Thu Aug 4 16:04:40 CDT 2011
>>
>>
>> dom0:
>> [barry at xen ~]$ cat /etc/issue
>> CentOS release 5.6 (Final)
>> Kernel \r on an \m
>>
>> [barry at xen ~]$ uname -a
>> Linux 2.6.18-238.19.1.el5xen #1 SMP Fri Jul 15 08:16:59 EDT 2011 x86_64
>> x86_64 x86_64 GNU/Linux
>>
>> [barry at xen ~]$ cat /proc/sys/xen/independent_wallclock
>> 0
>>
>> [barry at xen ~]# grep ntpd /var/log/messages
>> (snip)
>> Aug 3 11:04:27 xen ntpd[4008]: synchronized to 208.94.240.2, stratum 2
>> Aug 3 12:11:07 xen ntpd[4008]: synchronized to 209.114.111.1, stratum 2
>> Aug 4 03:50:07 xen ntpd[4008]: synchronized to 208.94.240.2, stratum 2
>> Aug 4 07:44:59 xen ntpd[4008]: synchronized to 209.114.111.1, stratum 2
>> Aug 4 09:49:03 xen ntpd[4008]: synchronized to 208.94.240.2, stratum 2
>> Aug 4 14:35:21 xen ntpd[4008]: synchronized to 209.114.111.1, stratum 2
>>
>> [barry at xen ~]# rpm -qa | grep xen
>> xen-libs-3.0.3-120.el5_6.3
>> kernel-xen-2.6.18-238.19.1.el5
>> kernel-xen-2.6.18-238.9.1.el5
>> xen-3.0.3-120.el5_6.3
>>
>>
>>
>> domU:
>> [barry at domU ~]$ cat /etc/issue
>> CentOS release 5.6 (Final)
>> Kernel \r on an \m
>>
>> [barry at domU ~]$ uname -a
>> Linux 2.6.18-238.19.1.el5 #1 SMP Fri Jul 15 07:31:24 EDT 2011 x86_64
>> x86_64 x86_64 GNU/Linux
>>
>> [barry at domU ~]$ cat /proc/sys/xen/independent_wallclock
>> cat: /proc/sys/xen/independent_wallclock: No such file or directory
>>
>> [barry at domU ~]$ rpm -qa | grep xen
>> (nothing)
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