Woah. That's a lot of wind. ;-) Here's what I've been doing for the last few years, that I'm completely happy with:
I configure the vmware hosts to get NTP from the internet (or whatever source you prefer.) (Configuration / Time Configuration / NTP Client). Then, Edit Settings of each guest, and go to Options/VMWare Tools, and there's a checkbox for "[X] Synchronize guest time with host" which is not checked by default. Make sure vmware-tools is running in your guest. And disable any NTP client in the guest. Easy peasy. The AD machines can be guests, and they can serve time to all the AD clients on the network. By doing it this way, everybody will be in-sync +/- a few seconds, which is good enough for most purposes. But if you have more stringent requirements, I guess you wouldn't need to have this discussion at all. ;-) From: tech-boun...@lists.lopsa.org [mailto:tech-boun...@lists.lopsa.org] On Behalf Of Mathew Snyder Sent: Tuesday, November 18, 2014 4:50 PM To: LOPSA Tech Subject: [lopsa-tech] Keeping time in sync in a VMware "cloud" environment We are currently in a situation where we are being pressured to re-engineer our NTP service. We currently host it, along with other services, on Windows DCs. Our initial plan is to move NTP off of those servers and host it on dedicated Linux servers. We likely won't get approval for hardware to host NTP and will thus have to rely on VMs. This poses a few concerns such as: How will a Vmotion affect the service? What happens if access to the sources that we use is lost (for whatever reason)? In the past, all of our VMs would run ntpd normally. That is, as a constantly running daemon.. However, we found that time was drifting significantly to the tune of several seconds a day on several servers. We never figured out why it was happening. Instead, we found that using a cron job which runs /usr/sbin/ntpd every five minutes kept time synced up nicely. We haven't had any issues since. However, now Red Hat is telling us we should (need) to be running ntpd as a daemon because they are seeing timing issues. Interestingly, this was never brought to the attention of us platform engineers so I don't know how bad the problem is or how many servers are affected. The problem could be VMware Tools conflicting with ntpd. But again, we don't know what the problem is. Only that we have a workaround-type solution that we're being told we have to replace. This leads to my question to the list: those of you who have cloud environments based on VMware solutions, how do you keep time in sync? What issues have you encountered and how did you solve those problems? What can you recommend for a virtualized NTP solution? -Mathew "When you do things right, people won't be sure you've done anything at all." - God; Futurama "We'll get along much better once you accept that you're wrong and neither am I." - Me
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