Linux server time getting out of sync frequently.

[Northrup, Wilson]

Hello Josh, 

If you don't mind, could you specify your configuration for those 70
guests?
Are you using VMware ESX server, or another VMware product?  What
version of VMware product and RHEL?
Are any running 64bit?

Thanks in advance
wilson
 

-----Original Message-----
From: redhat-list-bounces at redhat.com
[mailto:redhat-list-bounces at redhat.com]On Behalf Of Josh Miller
Sent: Tuesday, May 27, 2008 2:51 PM
To: General Red Hat Linux discussion list
Subject: Re: Linux server time getting out of sync frequently.


John Horne wrote:
>> as i recall, there are a few parameters you can set within the vmware
app
>> for the guest os, in order to sync the timing, and to stop the skew
from
>> occuring...
>>
>> i think you might also have to modify the kernel startup attributes.
>>
> The only solution I have found to work is to stop NTP on the guest and
> simply run ntpdate (getting the time from other reliable server) every
> hour or so via cron. The only 'solution' I have not tried is
rebuilding
> the kernel. Suggestions like use the PIT time source on the kernel
> startup line may well improve the timekeeping, but it still loses
time.

Hi, coming into this late, but I have been very successful with the
following solution:

1. make sure all ESX hosts are syncing time via NTP with a reliable
source
2. disable NTPD in all guests
3. set each guest to sync time via VMware tools by setting
tools.SyncTime=TRUE
4. in each guest, on the kernel line in grub.conf, set clock=pit and
reboot

That has been a bulletproof method for me with over 70 linux guests.

re:  http://www.vmware.com/pdf/vmware_timekeeping.pdf

HTH,
Josh Miller - RHCE, VCP

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