ankush grover wrote:
> Hi friends,
>
> I am running Nagios 2.7-1 on Centos 5.0 32-bit hosted on Vmware ESX
> 4.0. The issue I am seeing on the server is sometimes nagios is
> showing the below messages in /var/log/messages and as the system time
> gets changed some false alarms gets generated. I searched it on the
> google but I am not able to find the correct solution. I even posted
> on the nagios forum and they asked me to see elsewhere why the server
> shitfs so much before looking at nagios.

Well, VMWare ESX sometime causes time jumps

Possibly your service provider is overbooking cpu time of that ESX host ..

--
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ankush grover schrieb:
> Hi friends,
>
> I am running Nagios 2.7-1 on Centos 5.0 32-bit hosted on Vmware ESX
> 4.0. The issue I am seeing on the server is sometimes nagios is
> showing the below messages in /var/log/messages and as the system time
> gets changed some false alarms gets generated. I searched it on the
> google but I am not able to find the correct solution. I even posted
> on the nagios forum and they asked me to see elsewhere why the server
> shitfs so much before looking at nagios.
>
>
> Nov 21 20:37:12 linuxmonitoring nagios: Warning: A system time change
> of 4398 seconds (forwards in time) has been detected. Compensating...
> Nov 21 19:23:54 linuxmonitoring nagios: Warning: A system time change
> of 4398 seconds (backwards in time) has been detected. Compensating..
>
>
> Earlier this server was syncing time through ntp daemon and below is
> the ntp.conf file. Now I have set a cronjob which sync the time with
> the ntp server every 5 minutes but still the problem persist.
>
> ntp.conf file
>
>
> restrict default ignore
> restrict 127.0.0.1
> driftfile /var/lib/ntp/drift
> broadcastdelay 0.008
> #authenticate yes
> keys /etc/ntp/keys
> restrict 172.16.6.3 nomodify notrap noquery
> server 172.16.6.3
> restrict 172.16.6.2 nomodify notrap noquery
> server 172.16.6.2
>
> Please see the output of hwclock and date at the same time.
> hwclock
> Sat 21 Nov 2009 08:19:02 PM IST -0.496922 seconds
>
> date
> Sat Nov 21 20:19:55 IST 2009
>
>
> Please advice what I need to do to fix this error.
>
>
> Regards
>
> Ankush

Be sure that only 1 mechanism for syncing time is active for your VM:
either NTP client configuration through ntpd running (like you have) OR
through the VMware tools. Both being active will result in trouble.

VMware recommends to use time syncronisation through NTP within the VM.

To debug your time sources in NTP make use of "ntpq" and/or "ntpdc".

Regards

Alexander

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ankush grover wrote:

> Earlier this server was syncing time through ntp daemon and below is
> the ntp.conf file. Now I have set a cronjob which sync the time with

Best not to run NTP inside a ESX VM. I've never gotten NTP to sync
inside of VMware outside of a kernel with VMI enabled (no versions
of RHEL support VMI at this time as far as I know).

What I do for my ~40 ESX/ESXi hosts:
- Have your ESX hosts sync to a good NTP server
- Make sure vmware tools is installed and running correctly
(/etc/init.d/vmware-tools status)
- Enable time sync for your guest, either via the UI or via
this command in the guest(I have this command run in cron
every 5 minutes as I have seen for some reason time sync turn
itself off:
/usr/sbin/vmware-guestd --cmd "vmx.set_option synctime 0 1"
- On top of all of that I have another cron set to run ntpdate
every 5 minutes against a local NTP server:
/usr/sbin/ntpdate `cat /etc/ntp/step-tickers | grep -v #`

For providing NTP services themselves, currently I run 3 VMs
at each site with Fedora 8 with VMI enabled for the guest VM
(the kernel in FC8 supports VMI, I suspect newer Fedoras work
fine too I just have no reason to change right now). And I have
these FC8 VMs sync to internet hosts(mainly time.nist.gov) so
my internal ESX and other systems can sync against them(they
are load balanced behind a F5 BigIP).

from FC8 kernel log:
VMI: Found VMware, Inc. Hypervisor OPROM, API version 3.0, ROM version 1.0
vmi: registering clock event vmi-timer. mult=9483317 shift=22
Booting paravirtualized kernel on vmi
vmi: registering clock source khz=2260999
Time: vmi-timer clocksource has been installed.

I currently run roughly 400 VMs this way and don't have any
noticeable time-related issues.

nate

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Akemi Yagi wrote:
> for VMware products including ESX and ESXi. According to their
> current recommendations, " In all cases use NTP instead of VMware
> Tools periodic time synchronization."

I've been using vmware for 10 years, and I've never, ever ever
gotten NTP to hold sync inside of a VM outside of using a VMI
enabled kernel.

nate


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nate wrote:
> Akemi Yagi wrote:
>
>> for VMware products including ESX and ESXi. According to their
>> current recommendations, " In all cases use NTP instead of VMware
>> Tools periodic time synchronization."
>>
>
> I've been using vmware for 10 years, and I've never, ever ever
> gotten NTP to hold sync inside of a VM outside of using a VMI
> enabled kernel.
>

I've got more than 20 VMs spread over 5 machines (VMware Server 2.x),
both 32 and 64 bit (hosts and VMs) that hold time perfectly using NTP.

1) Make *SURE* that 'cpuspeed' and any BIOS 'power saving' modes are
disabled on your host and your VMs. Nothing screws timekeeping like
having the CPU speed vary.

2) Use 'divider=10' on your grub kernel boot lines for your virtual
machines.

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Benjamin Franz schrieb:
> nate wrote:
>> Akemi Yagi wrote:
>>
>>> for VMware products including ESX and ESXi. According to their
>>> current recommendations, " In all cases use NTP instead of VMware
>>> Tools periodic time synchronization."
>>>
>> I've been using vmware for 10 years, and I've never, ever ever
>> gotten NTP to hold sync inside of a VM outside of using a VMI
>> enabled kernel.
>>
>
> I've got more than 20 VMs spread over 5 machines (VMware Server 2.x),
> both 32 and 64 bit (hosts and VMs) that hold time perfectly using NTP.
>
> 1) Make *SURE* that 'cpuspeed' and any BIOS 'power saving' modes are
> disabled on your host and your VMs. Nothing screws timekeeping like
> having the CPU speed vary.
>
> 2) Use 'divider=10' on your grub kernel boot lines for your virtual
> machines.

That kernel parameter information is out of date with CentOS 5.4:

http://kb.vmware.com/selfservice/microsites/search.do?language=en_US&cmd=displayKC&externalId= 1006427

As Akemi said, users of VMware virtualization products (bare metal
hypervisor products like ESX/ESXi and the other solutions) should
closely follow the KB article recommendations which are frequently updated.

Alexander


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nate wrote:
> ankush grover wrote:
>
>
>> Earlier this server was syncing time through ntp daemon and below is
>> the ntp.conf file. Now I have set a cronjob which sync the time with
>>
>
> Best not to run NTP inside a ESX VM. I've never gotten NTP to sync
> inside of VMware outside of a kernel with VMI enabled (no versions
> of RHEL support VMI at this time as far as I know).
>
> What I do for my ~40 ESX/ESXi hosts:
> - Have your ESX hosts sync to a good NTP server
> - Make sure vmware tools is installed and running correctly
> (/etc/init.d/vmware-tools status)
> - Enable time sync for your guest, either via the UI or via
> this command in the guest(I have this command run in cron
> every 5 minutes as I have seen for some reason time sync turn
> itself off:
> /usr/sbin/vmware-guestd --cmd "vmx.set_option synctime 0 1"
> - On top of all of that I have another cron set to run ntpdate
> every 5 minutes against a local NTP server:
> /usr/sbin/ntpdate `cat /etc/ntp/step-tickers | grep -v #`
>
> For providing NTP services themselves, currently I run 3 VMs
> at each site with Fedora 8 with VMI enabled for the guest VM
> (the kernel in FC8 supports VMI, I suspect newer Fedoras work
> fine too I just have no reason to change right now). And I have
> these FC8 VMs sync to internet hosts(mainly time.nist.gov) so
> my internal ESX and other systems can sync against them(they
> are load balanced behind a F5 BigIP).
>
> from FC8 kernel log:
> VMI: Found VMware, Inc. Hypervisor OPROM, API version 3.0, ROM version 1.0
> vmi: registering clock event vmi-timer. mult=9483317 shift=22
> Booting paravirtualized kernel on vmi
> vmi: registering clock source khz=2260999
> Time: vmi-timer clocksource has been installed.
>
> I currently run roughly 400 VMs this way and don't have any
> noticeable time-related issues.
>
> nate
>
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>
>
The OP should also reference this document
http://kb.vmware.com/selfservice/microsites/search.do?language=en_US&cmd=displayKC&externalId= 1006427

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