On Wed, Jan 2, 2013 at 7:27 PM, James B. Byrne <byrnejb at harte-lyne.ca>wrote: > > > @James: Can you specifically cite why you manually power down each > > node? Have you tried tweaking your libvirt settings in the config > > file I noted in my earlier response to Robert? > > Two reasons. First, I am minimally familiar with kvm. The niceties of > the options for it is beyond my kin for the nonce. Second, libvirt > does not always work. I have had guests refuse to either suspend or > shutdown from an automatic request to do so. When shutdown is done > manually one discovers right away that there is a problem and which > guest is causing it. > > I hear ya. I've never had libvirt not work, but I've had an issue or two with VMs shortly after they were created (not production at that point). > > Set up a central NTP server and have your hosts (and not just VMs) > > connect to it. It could be the VM host, but doesn't need to be. > > Distribute the load to your NTP server and off of the public NTP pool > > by running an NTP server for your servers to poll [0] ... it's a good > > practice and everybody is happy. > > > > I do that as well. However, I run one on each host just to serve its > own guests and configure the host to run off our central ntp server. > > > > > > >> 4. On each guest have a cron job that checks for ntpd at regular > >> intervals which reports failures and restarts the time service as > >> necessary. We use: > >> JOBNAME="Check ntpd status and restart if required" ; \ > >> ntpstat > /dev/null && \ > >> if [[ $? -gt 0 ]]; then /sbin/service ntpd start; fi > >> > >> > > Why not configure the ntpd daemon and stick with that? > > It does update on its own [1]. And ntpstat prints out the interval, > > which matches the one mentioned at [1]. > > I don't believe the ntpstat script/job is necessary (I've never had to > > do more than set ntpd to run after configuring the servers it should > > poll). > > > > You misunderstand the purpose of the job. Netstat checks to see if > the daemon is actually running. If it is not then netstat returns a > non-zero exit code. If the ntpstat exit code is not zero then the > service script is invoked to restart it. Additionally, netstat writes > out to stderr that it could not find the daemon which gets emailed to > support. I probably should have used [[ ! $? -eq 0 ]] but what I have > written does work. > > We found ntpd just stoped on some guests upon occasion without any > visible trace of a cause. Not frequently but when it did happen it > was a nuisance to detect before clock drift on the guest caused some > failure or other. This job detects these occurrences and self > corrects. > > I'll have to check my hosts tomorrow and see if there's any drift. Thanks for the explanation. > These are all CentOS-6.3 hosts and guests. > > -- > *** E-Mail is NOT a SECURE channel *** > James B. Byrne mailto:ByrneJB at Harte-Lyne.ca > Harte & Lyne Limited http://www.harte-lyne.ca > 9 Brockley Drive vox: +1 905 561 1241 > Hamilton, Ontario fax: +1 905 561 0757 > Canada L8E 3C3 > > _______________________________________________ > CentOS-virt mailing list > CentOS-virt at centos.org > http://lists.centos.org/mailman/listinfo/centos-virt > -- ---~~.~~--- Mike // SilverTip257 // -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.centos.org/pipermail/centos-virt/attachments/20130102/3c367d13/attachment-0006.html>