I am not sure if vmware sync clock really works I have read that paper since 2006 and never worked in my vmware environments, added kernel parameters, time sync and always ended up with ntp :-/ -- LSC On 9/3/08, Jeremy Schneider <jeremy.schneider@xxxxxxxxxxxxxx> wrote: > > Thought this thread might be useful to someone, someday. :) > > ---------- Forwarded message ---------- > Subject: Re: Time synchronization problem for VMWare with RAC and Linux > setup > To: Eugene Plagge > Cc: Dan Norris, Ben Prusinski > > > Yeah, IMHO it's best not to involve NTP with VMs. Time sync is a rather > complex issue for virtual environments (VMware has had large problems in > this area). Here's a great paper on the topic: > http://www.vmware.com/pdf/vmware_timekeeping.pdf > > For your test RAC cluster the VMware clock sync option should work fine - > we used it for all of the workstations during the lab in Chicago and didn't > have any problems. You mentioned that the VM's aren't in sync with each > other - are they in sync with the server? > > On older versions of linux I always used to add the kernel parameter > "clock=pit" and this helped with clock drift. You might try that too if > you're having drift problems. > > -Jeremy > > > > On Tue, Sep 2, 2008 at 3:38 PM, Eugene Plagge wrote: > > >> Thanks, Dan, >> >> Good tip about using ntp like that. We'll let you know if we discover >> anything else interesting. >> >> >> >> Eugene >> >> >> >> >> >> *From:* Dan Norris >> *Sent:* Tuesday, September 02, 2008 4:23 PM >> *To:* Eugene Plagge; Jeremy Schneider >> *Cc:* Ben Prusinski >> *Subject:* Re: Time synchronization problem for VMWare with RAC and Linux >> setup >> >> >> >> Hi Eugene, >> >> As Ben pointed out, the VMWare Tools should handle the synchronization. If >> there's no internet access from the machines, it is possible to set the >> machines to sync to one another using NTP (as peers) I believe. That way, >> they may both be off of the "real" time, but they should at least be sync'd >> with each other and that should allow you to complete the installation. >> >> In the worst case, if you set the clocks on each node to be the same >> within a few seconds, you should be able to complete the installations >> successfully. In that case, when the nodes reboot, you may have one or the >> other of them fail to join the cluster if the clocks aren't in sync. >> >> Let me know if that doesn't do the trick. Jeremy may also add in his own >> ideas. >> >> Dan >> >> >> On 9/2/08 3:10 PM, "Eugene Plagge" wrote: >> >> Hi, Jeremy and Dan, >> I attended the RAC Attack a few weeks ago. A colleague and I are having a >> problem setting up Linux VM machines. >> The time synchronization does not seem to be working (please see Ben's >> email below). I am having similar problems. >> >> Any hints or avenues we can try? >> >> Thanks very much, >> >> >> **** >> >> *From:* Ben Prusinski >> *Sent:* Tuesday, September 02, 2008 12:30 PM >> *To:* Doug Hahn >> *Cc:* Eugene Plagge >> *Subject:* Time synchronization problem for VMWare with RAC and Linux >> setup >> >> >> Thanks Doug will do. >> >> >> >> >> >> Hello Gene- >> >> >> >> I am having problems with my test 2-node RAC setup for Linux on VMWare. >> The issue is time synchronization for ntp and system clock for both VM >> machines in the cluster. I installed VMWare tools on both Linux VM guest OS >> machines to synchronize the time (via the option in the tools menu) but >> still they are not in sync. This will cause the RAC clusterware installation >> to fail if both nodes are not in sync with each other. Currently, both test >> VM machines do not have internet access so I am not able to use the internet >> NTP servers that are recommended. If you have been able to solve this >> problem, definitely would appreciate your insight and tips. >> >> >> >> Thanks in advance, >> >> Ben >> >> >> ** >> > > > > -- > Jeremy Schneider > Chicago, IL > http://www.ardentperf.com/category/technical > > >