From owner-freebsd-questions@FreeBSD.ORG Mon Nov 17 20:08:50 2008 Return-Path: Delivered-To: questions@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id BF32D1065673 for ; Mon, 17 Nov 2008 20:08:50 +0000 (UTC) (envelope-from jdc@koitsu.dyndns.org) Received: from QMTA03.emeryville.ca.mail.comcast.net (qmta03.emeryville.ca.mail.comcast.net [76.96.30.32]) by mx1.freebsd.org (Postfix) with ESMTP id 9D2EF8FC0C for ; Mon, 17 Nov 2008 20:08:50 +0000 (UTC) (envelope-from jdc@koitsu.dyndns.org) Received: from OMTA07.emeryville.ca.mail.comcast.net ([76.96.30.59]) by QMTA03.emeryville.ca.mail.comcast.net with comcast id gFZ81a0011GXsucA3L8qkB; Mon, 17 Nov 2008 20:08:50 +0000 Received: from koitsu.dyndns.org ([69.181.141.110]) by OMTA07.emeryville.ca.mail.comcast.net with comcast id gL8p1a00G2P6wsM8TL8p9i; Mon, 17 Nov 2008 20:08:49 +0000 X-Authority-Analysis: v=1.0 c=1 a=CCw1NJCUhGoA:10 a=Yr5oENspLq8A:10 a=QycZ5dHgAAAA:8 a=4KoO2YX1LovSym-8e9cA:9 a=_ux4B4UbW8gy6Bb6l6gA:7 a=OOWjY0TcgCetDJHP7bUUvPP1RwoA:4 a=EoioJ0NPDVgA:10 a=MSl-tDqOz04A:10 a=LY0hPdMaydYA:10 Received: by icarus.home.lan (Postfix, from userid 1000) id 5D93E33C37; Mon, 17 Nov 2008 12:08:49 -0800 (PST) Date: Mon, 17 Nov 2008 12:08:49 -0800 From: Jeremy Chadwick To: "N.J. Thomas" Message-ID: <20081117200849.GA38672@icarus.home.lan> References: <5635aa0d0811140711t6af42ef8i762a37eb059ede19@mail.gmail.com> <20081117173845.GM91662@zaph.org> <26ddd1750811171147u5cc8f9b3k35f25c6caf9bc14f@mail.gmail.com> <20081117200102.GN91662@zaph.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20081117200102.GN91662@zaph.org> User-Agent: Mutt/1.5.18 (2008-05-17) Cc: Maxim Khitrov , questions@freebsd.org Subject: Re: FreeBSD not stable enough for Xen environments? X-BeenThere: freebsd-questions@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: User questions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 17 Nov 2008 20:08:50 -0000 On Mon, Nov 17, 2008 at 03:01:02PM -0500, N.J. Thomas wrote: > * Maxim Khitrov [2008-11-17 14:47:00+0000]: > > > I've not seen any problems with the clock on my RootBSD Xen system. > > > I do run the ntpd in base and on average, my clock is usually only > > > about 15ms away from "true UTC". > > > > That's interesting. Can you post your `ntpq -p` output here? > > Sure: > > $ ntpq -p > remote refid st t when poll reach delay offset jitter > ============================================================================== > +clock.trit.net 192.12.19.20 2 u 529 1024 377 81.554 2.870 6.477 > +mail.honeycomb. 192.43.244.18 2 u 408 1024 377 44.091 10.986 8.250 > *tuppy.intrepidh 64.142.103.194 2 u 413 1024 377 67.709 15.626 10.327 > +clock3.redhat.c 66.187.233.4 2 u 445 1024 377 147.283 24.455 9.397 > +204.34.198.40 .USNO. 1 u 409 1024 377 88.746 20.620 10.405 > +tick.usno.navy. .USNO. 1 u 427 1024 377 20.848 18.916 8.212 > +ntp-s1.cise.ufl .GPS. 1 u 421 1024 377 45.709 18.067 9.222 > LOCAL(0) LOCAL(0) 10 l 18 64 377 0.000 0.000 0.004 > > This is what I pretty much used to eyeball my offset earlier. > > > When ntpd is running, its polling interval stays very low (around 64 > > seconds) because it keeps having to reset the clock. My message log is > > filled with the following: > > Intersting, I see the same in my logs, but the frequency seems to be > much less than yours, e.g. for the month of November: > > Nov 1 00:08:22 zaph ntpd[678]: time reset -0.129649 s > Nov 3 15:33:09 zaph ntpd[678]: time reset -0.137509 s > Nov 4 03:11:51 zaph ntpd[678]: time reset +0.237734 s > Nov 4 03:34:23 zaph ntpd[678]: time reset -0.150326 s > Nov 4 13:05:20 zaph ntpd[678]: time reset +0.317738 s > Nov 4 13:32:06 zaph ntpd[678]: time reset -0.560629 s > Nov 4 13:54:35 zaph ntpd[678]: time reset +0.265391 s > Nov 4 15:43:55 zaph ntpd[678]: time reset -0.163660 s > Nov 7 17:31:03 zaph ntpd[678]: time reset -0.130039 s > Nov 10 18:29:19 zaph ntpd[678]: time reset +0.169785 s > Nov 10 19:46:26 zaph ntpd[678]: time reset -0.146554 s > Nov 10 20:27:08 zaph ntpd[678]: time reset +0.891811 s > Nov 10 20:53:59 zaph ntpd[678]: time reset -0.774636 s > Nov 10 21:35:45 zaph ntpd[678]: time reset +0.384227 s > Nov 10 22:33:46 zaph ntpd[678]: time reset -0.194131 s > Nov 11 12:34:25 zaph ntpd[678]: time reset +0.433002 s > Nov 11 13:01:09 zaph ntpd[678]: time reset -0.335592 s > Nov 11 15:17:45 zaph ntpd[678]: time reset +0.933537 s > Nov 11 16:01:42 zaph ntpd[678]: time reset -0.510371 s > Nov 11 17:29:41 zaph ntpd[678]: time reset -0.133244 s > Nov 11 19:16:41 zaph ntpd[678]: time reset +0.191431 s > Nov 11 19:42:30 zaph ntpd[678]: time reset -0.458738 s > Nov 11 20:09:16 zaph ntpd[678]: time reset +0.207999 s > Nov 11 20:36:06 zaph ntpd[678]: time reset +0.143897 s > Nov 14 01:29:44 zaph ntpd[678]: time reset +0.134492 s > Nov 15 13:13:36 zaph ntpd[678]: time reset +0.199937 s > Nov 15 14:45:09 zaph ntpd[678]: time reset -0.205131 s What time counter source does this box have available? The following will list what's being used (hardware) and what's available (choice): sysctl kern.timecounter.choice sysctl kern.timecounter.hardware Other ideas: Look into the "fudge" operator of ntp.conf. Try deleting your ntp driftfile. Note that if you do this, it will take a day or two for things to "level out". It tries to figure out the "average" skew rate your system clock has. > > And so on... Could it be a problem with the hardware on host machine? > > I use the same ntp.conf file on several FreeBSD 7.1 servers, and the > > VPS is the only one that has this problem. > > I checked on my other FreeBSD boxes (all 7.0) and none of them (VPS or > otherwise) exihibit this problem. Then there's a very good possibility it's hardware-related. At my workplace, we've had two separate machines in the past couple months had clocks which "went crazy" -- ntpd reporting 4-5 seconds of skew every 25-30 minutes. In both cases, the problem turned out to be broken/bad hardware (crystal or TSC gone bad). Just something to keep in mind. :-) -- | Jeremy Chadwick jdc at parodius.com | | Parodius Networking http://www.parodius.com/ | | UNIX Systems Administrator Mountain View, CA, USA | | Making life hard for others since 1977. PGP: 4BD6C0CB |