<div dir="ltr">On Wed, Jan 2, 2013 at 7:27 PM, James B. Byrne <span dir="ltr"><<a href="mailto:byrnejb@harte-lyne.ca" target="_blank">byrnejb@harte-lyne.ca</a>></span> wrote:<br><div class="gmail_extra"><div class="gmail_quote">
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div class="im"><br>> @James: Can you specifically cite why you manually power down each<br>
> node? Have you tried tweaking your libvirt settings in the config<br>
> file I noted in my earlier response to Robert?<br>
<br>
</div>Two reasons. First, I am minimally familiar with kvm. The niceties of<br>
the options for it is beyond my kin for the nonce. Second, libvirt<br>
does not always work. I have had guests refuse to either suspend or<br>
shutdown from an automatic request to do so. When shutdown is done<br>
manually one discovers right away that there is a problem and which<br>
guest is causing it.<br>
<div class="im"><br>
</div></blockquote><div><br></div><div style>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).</div><div> </div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<div class="im">> Set up a central NTP server and have your hosts (and not just VMs)<br>
> connect to it. It could be the VM host, but doesn't need to be.<br>
> Distribute the load to your NTP server and off of the public NTP pool<br>
> by running an NTP server for your servers to poll [0] ... it's a good<br>
> practice and everybody is happy.<br>
><br>
<br>
</div>I do that as well. However, I run one on each host just to serve its<br>
own guests and configure the host to run off our central ntp server.<br>
<div class="im"><br>
><br>
><br>
>> 4. On each guest have a cron job that checks for ntpd at regular<br>
>> intervals which reports failures and restarts the time service as<br>
>> necessary. We use:<br>
>> JOBNAME="Check ntpd status and restart if required" ; \<br>
>> ntpstat > /dev/null && \<br>
>> if [[ $? -gt 0 ]]; then /sbin/service ntpd start; fi<br>
>><br>
>><br>
> Why not configure the ntpd daemon and stick with that?<br>
> It does update on its own [1]. And ntpstat prints out the interval,<br>
> which matches the one mentioned at [1].<br>
> I don't believe the ntpstat script/job is necessary (I've never had to<br>
> do more than set ntpd to run after configuring the servers it should<br>
> poll).<br>
><br>
<br>
</div>You misunderstand the purpose of the job. Netstat checks to see if<br>
the daemon is actually running. If it is not then netstat returns a<br>
non-zero exit code. If the ntpstat exit code is not zero then the<br>
service script is invoked to restart it. Additionally, netstat writes<br>
out to stderr that it could not find the daemon which gets emailed to<br>
support. I probably should have used [[ ! $? -eq 0 ]] but what I have<br>
written does work.<br>
<br>
We found ntpd just stoped on some guests upon occasion without any<br>
visible trace of a cause. Not frequently but when it did happen it<br>
was a nuisance to detect before clock drift on the guest caused some<br>
failure or other. This job detects these occurrences and self<br>
corrects.<br>
<br></blockquote><div><br></div><div style>I'll have to check my hosts tomorrow and see if there's any drift.</div><div style>Thanks for the explanation.</div><div> </div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
These are all CentOS-6.3 hosts and guests.<br>
<div class="im HOEnZb"><br>
--<br>
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James B. Byrne mailto:<a href="mailto:ByrneJB@Harte-Lyne.ca">ByrneJB@Harte-Lyne.ca</a><br>
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<br>
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</div></div></blockquote></div><br>-- <br>---~~.~~---<br>Mike<br>// SilverTip257 //
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