NTP problem for virtual RHEL 4 server on VmWare

[Kenneth Holter]

We adjusted the kernel parameters this morning, and the result looks
promising:


13 Nov 08:01:02 ntpdate[6253]: adjust time server 1.2.3.4 offset 0.041978
sec
13 Nov 09:01:01 ntpdate[14110]: adjust time server 1.2.3.4 offset -0.426118
sec
13 Nov 10:01:02 ntpdate[24901]: adjust time server 1.2.3.4 offset -0.151613
sec
13 Nov 11:01:01 ntpdate[3253]: adjust time server 1.2.3.4 offset 0.244806
sec
13 Nov 12:01:01 ntpdate[14023]: adjust time server 1.2.3.4 offset 0.256945
sec
13 Nov 13:01:02 ntpdate[25138]: adjust time server 1.2.3.4 offset -0.058973
sec
13 Nov 14:01:01 ntpdate[3482]: adjust time server 1.2.3.4 offset 0.144722
sec
13 Nov 15:01:01 ntpdate[12936]: adjust time server 1.2.3.4 offset -0.019486
sec


I'll keep monitoring it, but if nothing else comes up I think I'll settle
for this solution.

Thansk for all the help.


Regards,
Kenneth


On 11/13/08, Kenneth Holter <kenneho.ndu at gmail.com> wrote:
>
>
> Interesting observation. Our troublesome VM has been running for quite a
> log while, though, and it still seems quite unstable. We just rebooted it
> with the kernel parameters mentioned in http://kb.vmware.com/kb/1006427 (thank
> you Mr. Dill), and I'll post the results back here in a day or two.
> Hopefully it will solve our problem, even thogh it didn't solve yours.
>
> What puzzles me is why this VM drifts so much, while most of our other VMs
> doens't (at least not more than NTPd can handle).
>
>
>  On 11/12/08, Eric Sisler <lbylnxgek at gmail.com> wrote:
>>
>> On Fri, Nov 7, 2008 at 2:49 AM, Kenneth Holter <kenneho.ndu at gmail.com
>> >wrote:
>>
>> > Hei.
>> >
>> >
>> > One of our RHEL 4 servers running on VmWare has a quite serious NTP
>> > problem.
>> > I know that NTP can be an issue when running red hat boxes on VmWare, so
>> as
>> > a fix I put this small script in a file in /etc/cron.hourly:
>>
>>
>>
>> Early on I went through the frustrations with time & NTP problems on RHEL
>> 4
>> virtual machines.  I've used a number of the earlier suggestions,
>> including
>> various boot time  & VMware configuration options.  I even went so far as
>> to
>> compile a custom kernel with the clock frequency set back to 100, as it
>> was
>> for the 2.4.x kernels.  Overall it didn't seem like any of the boot time
>> or
>> VMware config options made that much difference.  Recompling the kernel
>> works, but gets to be a lot of overhead after awhile.
>>
>> Now for the odd part:  Currently my RHEL4 VMs have time sync enabled in
>> the
>> VMware config file & also have NTP running.  It seems that the longer NTP
>> runs, the more accurate the time gets on the VM.  When booting a "new" VM,
>> it wasn't uncommon for NTP to adjust the time by 20-30 seconds.  Once the
>> VM
>> gets a bit "older" & NTP has been running longer, when rebooting the VM
>> clock adjustment goes down to around 5-6 seconds.  I suspect part of this
>> has to do with the frequency & adjustment history recorded by NTP.
>>
>> The updated VMware KB may be of some help as well.  Good luck!
>>
>> -Eric
>> --
>> redhat-list mailing list
>> unsubscribe mailto:redhat-list-request at redhat.com?subject=unsubscribe
>> https://www.redhat.com/mailman/listinfo/redhat-list
>>
>
>