Re: [CentOS-virt] Time

On Wed, Jan 2, 2013 at 3:53 AM, Robert Dinse nanook@eskimo.com wrote:

 Friday, I moved our servers to a new co-lo facility and ran into an

interesting problem with virtual machines.

 I did an orderly shutdown of the CentOS 6.3 host, and it in turn

suspends all the guests. It took about an hour and a half to move and fire up the host.

By default VMs suspend when the host node is shutdown. You can change this behavior in /etc/sysconfig/libvirt-guests

By shutting down the VMs you don't have to wait for the in-memory data to be dumped to disk, nor do you have to wait for it to be copied back from disk and into memory on boot.

 The guests, being suspended, were then an hour and a half behind and

it seems ntpd does not want to correct more than 1000 seconds of error so it would not automatically adjust the clocks.

At my place of employment we noticed the same thing during maintenance, the VMs had their clocks all out of whack.

 I tried the -g argument which is supposed to override the 1000 second

limit but it did not. I ended up having to manually set the clocks close enough for ntpd to correct.

I believe we had manually correct the clocks as well on ours, but it's been months since then.

 Since there is no hardware clock for the virtual machines to use when

they boot, it seems that shutdown and reboot of the virtual machines probably would not have avoided this.

 Any suggestions for addressing this particular scenerio other than

having to manually set a bunch of clocks?

-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_- Eskimo North Linux Friendly Internet Access, Shell Accounts, and Hosting. Knowledgeable human assistance, not telephone trees or script readers. See our web site: http://www.eskimo.com/ (206) 812-0051 or (800) 246-6874 .

---

CentOS-virt mailing list CentOS-virt@centos.org http://lists.centos.org/mailman/listinfo/centos-virt