Chris's Wiki :: blog/sysadmin/NTPDaemonWhen Commentshttps://utcc.utoronto.ca/~cks/space/blog/sysadmin/NTPDaemonWhen?atomcommentsDWiki2017-11-18T23:30:20ZRecent comments in Chris's Wiki :: blog/sysadmin/NTPDaemonWhen.By Twirrim on /blog/sysadmin/NTPDaemonWhentag:CSpace:blog/sysadmin/NTPDaemonWhen:d0403c8075a683df579f34988e1d6806ffc46de6Twirrim<div class="wikitext"><p>Running an NTP daemon is often very important if your servers are virtualised. The hypervisor compresses and expands the gaps between timer interrupts as befits the expectations of the host operating system as well as the hypervisor process itself. This can cause all sorts of complications with VMs running under the hypervisor.</p>
<p>Even this advice gets conflicted, Canonical says one thing, RedHat another and so on.</p>
<p>Also to add complexity to the mix, KVM has a clock for paravirtualised instances on it, which allow them to sync to the host clock natively: <a href="https://rwmj.wordpress.com/tag/kvmclock/">https://rwmj.wordpress.com/tag/kvmclock/</a></p>
<p>Honestly? It takes so little effort and resources, I'd generally rather run an NTP daemon than not.</p>
</div>2017-11-18T23:30:20ZBy Chris Siebenmann on /blog/sysadmin/NTPDaemonWhentag:CSpace:blog/sysadmin/NTPDaemonWhen:7cfca38ac8c520b55589a5e5921b23189282aa78Chris Siebenmann<div class="wikitext"><p>I think that all your machines should be time sync'd. The question for
me is how closely. Running an NTP daemon is necessary if the answer is
'within a few milliseconds', but if the answer is 'within a hundredth
of a second', you can almost certainly just run ntpdate/sntp/etc from
cron every hour. For a central syslog server, well, syslog timestamps
are only to the second.</p>
<p>(And with a central syslog server I prefer to have the server add
the timestamps, not the clients, because that automatically makes all
messages use the same time base no matter what the clients have happen
to their clocks.)</p>
</div>2017-11-17T16:35:29ZBy D. Ebdrup on /blog/sysadmin/NTPDaemonWhentag:CSpace:blog/sysadmin/NTPDaemonWhen:0daa0760b39e5040da4df9b18259784477be0b25D. Ebdruphttp://blog.nullrouted.org<div class="wikitext"><p>In general, my philosophy is that any machine whose logging gets synchronized to a central logging repository needs to be time sync'd, as well.</p>
<p>But then, I also maintain my own time server from a GPS signal, mostly because I can.</p>
</div>2017-11-17T16:30:09Z