With the exception of a handful of RHEL 5.8 VMs we run RHEL 6.4 and 6.5. According to VMware no additional tuning parameters should be needed.
-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 On Tue, Nov 18, 2014 at 4:19 PM, Brian Mathis < brian.mathis+lo...@betteradmin.com> wrote: > I don't believe ntpdate has ever been a recommendation. They started out > telling people to use the time sync through vmware tools (which is similar > to ntpdate and makes sense in a VMware Workstation environment), then went > to using ntpd running as a daemon, potentially with the kernel tuning > parameters. > > Both vmware tools and ntpdate have the huge problems of jolting the clock > to the correct time and the possibility of time going backwards. An ntp > daemon, on the other hand, slows down and speeds up the clock to keep it in > sync. Anything sensitive to time is going to have a problem with methods > that jolt the time around. > > Using ntpdate in cron is a duct tape solution and doesn't actually fix the > problem, it just covers it up. The only real solution is to follow that > VMware KB article and get ntpd tuned correctly. If that doesn't work, open > a VMware support ticket? > > However, all of this is really a discussion about clients. Running an ntp > server from a VM will be a lot more problematic. You're best bet there is > to get a dedicated hardware time source, like a GPS or something. > Otherwise, the global ntp pool (http://www.pool.ntp.org) is not a bad > solution. It's relatively secure since you're querying a giant pool of > servers and it would be pretty amazing if all of them were compromised at > once to serve bad time. > > > ❧ Brian Mathis > @orev > > > > On Tue, Nov 18, 2014 at 4:55 PM, Matt Simmons <msimm...@lopsa.org> wrote: > >> As of a major version ago on ESXi, it was considered best practice to run >> ntpdate in a cron rather than ntpd on VMs, particularly if you weren't >> using the most up-to-date VMware tools (and I believe they recommended the >> VMware version, rather than open-vm tools). >> >> I've also seen that behavior when a VM Host had a screwed up NTP config. >> >> I haven't noticed any significant clock skew during a vmotion, but I've >> never checked it. I can give it a shot if you'd like. >> >> --Matt >> >> >> On Tue, Nov 18, 2014 at 4:50 PM, Mathew Snyder <mathew.sny...@gmail.com> >> wrote: >> >>> 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 >>> >>> _______________________________________________ >>> Tech mailing list >>> Tech@lists.lopsa.org >>> https://lists.lopsa.org/cgi-bin/mailman/listinfo/tech >>> This list provided by the League of Professional System Administrators >>> http://lopsa.org/ >>> >>> >> >> _______________________________________________ >> Tech mailing list >> Tech@lists.lopsa.org >> https://lists.lopsa.org/cgi-bin/mailman/listinfo/tech >> This list provided by the League of Professional System Administrators >> http://lopsa.org/ >> >> > > _______________________________________________ > Tech mailing list > Tech@lists.lopsa.org > https://lists.lopsa.org/cgi-bin/mailman/listinfo/tech > This list provided by the League of Professional System Administrators > http://lopsa.org/ > >
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