[CentOS] system time automatically fowards in time and then comes back to normal

Clint Dilks clintd at scms.waikato.ac.nz
Sun Nov 22 20:19:01 UTC 2009

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

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