| Isaac Bennetch on 8 Jul 2015 11:40:38 -0700 |
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| Re: [PLUG] ntp |
I believe ntpd attempts to compensate for drift; which is great if your system clock is drifting at a consistent rate because of some internal timing error. It's less helpful if you're like me and have a virtual machine (virtualbox in my case) that somehow gets fewer clock cycles when not in the foreground (or heaven forbid you suspend/pause the machine!). If the machine was in the foreground a lot, it would run faster than real speed (with the ntpd drift compensation this could be something like a minute fast per hour) or in the background it could lose time at a shocking rate. In particular, the shock came after running git commit then wondering why I couldn't find the commit at the top of git log :-) My solution was also to run ntpdate on some schedule, which isn't what I would call production hardened but is good enough for my uses. There was supposedly a vntp program, for virtual ntp, which was designed to overcome this. For some reason I'm not using it, so it mustn't have worked right or I didn't figure out installation or some such. Kind regards, Isaac > On Jul 8, 2015, at 2:15 PM, Walt Mankowski <waltman@pobox.com> wrote: > > But...but... > > You do realize that's essentially what ntpd does, only ntpd does it > way better, right? > > Right? > >> On Wed, Jul 08, 2015 at 01:37:59PM -0400, Keith C. Perry wrote: >> That's what I do. Run "ntpdate us.pool.ntp.org" every 4 to 6 hours on critical / core systems. >> >> >> ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ >> Keith C. Perry, MS E.E. >> Owner, DAO Technologies LLC >> (O) +1.215.525.4165 x2033 >> (M) +1.215.432.5167 >> www.daotechnologies.com >> >> >> From: "Bill East" <wm.east@gmail.com> >> To: "Philadelphia Linux User's Group Discussion List" <plug@lists.phillylinux.org> >> Sent: Wednesday, July 8, 2015 1:35:29 PM >> Subject: Re: [PLUG] ntp >> >> >> >> I just had to deal with a vendor installation which was about 4 seconds off the ntp server it was supposed to be synced with. Come to find out the vendor ran a ntpdate command once a day and the vm was drifting 4 seconds in the 24 hours between. Their solution was to run the command once an hour instead. >> On Jul 8, 2015 1:13 PM, "Eric Riese" < eric.riese@gmail.com > wrote: >> >> >> >> So I just noticed that my KVM server's clocks were way off. The host OS was 4 minutes behind time.gov and the guests were 4 minutes ahead of time.gov . >> >> Turns out the host did not have ntp installed at all. It's Ubuntu 12.04 and was installed as some sort of minimal installation. A sudo apt-get install ntp and five minutes later it's in good shape. >> >> The guests are debian installs from turnkeylinux.org and they have ntp installed but were not running by default! >> >> To think, Google runs it's own internal NTP servers and had to spread the leap second out over a day, and I'm off by whole minutes! >> >> ___________________________________________________________________________ >> Philadelphia Linux Users Group -- http://www.phillylinux.org >> Announcements - http://lists.phillylinux.org/mailman/listinfo/plug-announce >> General Discussion -- http://lists.phillylinux.org/mailman/listinfo/plug >> >> >> >> >> >> ___________________________________________________________________________ >> Philadelphia Linux Users Group -- http://www.phillylinux.org >> Announcements - http://lists.phillylinux.org/mailman/listinfo/plug-announce >> General Discussion -- http://lists.phillylinux.org/mailman/listinfo/plug > >> ___________________________________________________________________________ >> Philadelphia Linux Users Group -- http://www.phillylinux.org >> Announcements - http://lists.phillylinux.org/mailman/listinfo/plug-announce >> General Discussion -- http://lists.phillylinux.org/mailman/listinfo/plug > > ___________________________________________________________________________ > Philadelphia Linux Users Group -- http://www.phillylinux.org > Announcements - http://lists.phillylinux.org/mailman/listinfo/plug-announce > General Discussion -- http://lists.phillylinux.org/mailman/listinfo/plug ___________________________________________________________________________ Philadelphia Linux Users Group -- http://www.phillylinux.org Announcements - http://lists.phillylinux.org/mailman/listinfo/plug-announce General Discussion -- http://lists.phillylinux.org/mailman/listinfo/plug