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6 Replies Last post: Apr 14, 2009 12:16 PM by Byron_Zhao

Linux VM time sync

Apr 8, 2009 5:53 AM

Byron_Zhao 124 posts since
Nov 7, 2006

This is an old topic, but recently a colleage draw my attention to an document at Linux Install Config.

I believe VMware used to recommend to use VMware tools to sync Linux VM's time clock to the ESX host. However, in this documen's page 14, it said "Whenever possible, use NTP instead of VMware Tools periodic time synchronization."

The time issue was a real pain before. It stopped for a while. Now I see this 180 degree of change, not sure what I should follow.

How is everyone else doing with time sync in Linux VM out there?

BTW, my environment mainly use Red Hat.

Tags: esx3.5, guest_os, linux, time

Reply Re: Linux VM time sync Apr 8, 2009 7:37 AM

RParker 5,270 posts since
Dec 6, 2006

page 14, it said "Whenever possible, use NTP instead of VMware Tools periodic time synchronization."

This is the correct method. You should ALWAYS use NTP whenever possible. ALWAYS. The 'synch' from the tools is a poor man's method, and it's very basic. Plus if your server somehow get's the wrong time, ALL your VM's will now synch incorrectly, so it's best that each client get their own source.

Even if they all point to the same NTP source, it's best to configure Linux VM's with NTP, and not use the tools. Your ESX host woud become the source of failure if something were to happen.

Reply Re: Linux VM time sync Apr 8, 2009 11:42 AM

in response to: RParker

Byron_Zhao 124 posts since
Nov 7, 2006

In my previous job, we were told to sync time to ESX hosts. At that time we had about 300 VMs, and luckly we found a way to have all the Windows and Linux VM sync to the ESX hosts. It was working fine for the Windows VM and 32bit Linux VM, while some problems were still with the 64bit Linux VM. Now that this doc said I should use NTP. It is kind of frustrating. I guess I haven't followed close enough on the best practice for ESX.

As for ESX is the source of failure, the time in our ESX servers always have the correct time whenever I check it.

Reply Re: Linux VM time sync Apr 8, 2009 11:46 AM

in response to: Byron_Zhao

Chamon 822 posts since
Aug 15, 2007

What is their time source?

Reply Re: Linux VM time sync Apr 14, 2009 6:25 AM

in response to: Chamon

Byron_Zhao 124 posts since
Nov 7, 2006

Was on vacation and couldn't get back earlier.

Anyway, the time source for our ESX is out NTP appliance. The time source Linux VM is ESX by syncing through VMware tools.Since now the recommendation from VMware has been change to use NTP, I guess that is the route we are going to take for the VMs that are experiencing time problems.

Thanks