From owner-freebsd-xen@freebsd.org Tue Nov 3 10:04:02 2015 Return-Path: Delivered-To: freebsd-xen@mailman.ysv.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) by mailman.ysv.freebsd.org (Postfix) with ESMTP id C0AFAA2349D for ; Tue, 3 Nov 2015 10:04:02 +0000 (UTC) (envelope-from kpielorz_lst@tdx.co.uk) Received: from smtp.krpservers.com (smtp.krpservers.com [62.13.128.145]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client CN "*.krpservers.com", Issuer "RapidSSL SHA256 CA - G3" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id 5E5551B38 for ; Tue, 3 Nov 2015 10:04:01 +0000 (UTC) (envelope-from kpielorz_lst@tdx.co.uk) Received: from [10.12.30.106] (vpn01-01.tdx.co.uk [62.13.130.213] (may be forged)) (authenticated bits=0) by smtp.krpservers.com (8.14.9/8.14.9) with ESMTP id tA3A3oFA003675 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO); Tue, 3 Nov 2015 10:03:52 GMT (envelope-from kpielorz_lst@tdx.co.uk) Date: Tue, 03 Nov 2015 10:03:50 +0000 From: Karl Pielorz To: =?UTF-8?Q?Roger_Pau_Monn=C3=A9?= , freebsd-xen@freebsd.org Subject: Re: 'Live' Migrate messes up NTP on FreeBSD domU - any suggestions? Message-ID: <8448B4CE863936ADEF762C0F@[10.12.30.106]> In-Reply-To: <5637A01B.1010307@citrix.com> References: <151F73F1EF071C3C48F17866@[10.12.30.106]> <5637A01B.1010307@citrix.com> X-Mailer: Mulberry/4.0.8 (Win32) MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Content-Disposition: inline X-BeenThere: freebsd-xen@freebsd.org X-Mailman-Version: 2.1.20 Precedence: list List-Id: Discussion of the freebsd port to xen - implementation and usage List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 03 Nov 2015 10:04:02 -0000 Hi, Ok, I've done some proper research into this now... When Migrating a domU FreeBSD (10.1-R p6) between hosts, it "more often than not" gains time. This breaks NTP on the domU. I setup a script on the domU being migrated that read out it's clock - and called out to an external machine to read it's clock - i.e. " Me: Tue Nov 3 09:55:51 GMT 2015 Them: Tue Nov 3 09:55:51 GMT 2015 Me: Tue Nov 3 09:55:52 GMT 2015 Them: Tue Nov 3 09:55:52 GMT 2015 " As you can see 'Me' and 'Them' is in sync. At this point I live migrated the FreeBSD box from one XenServer (6.5-SP1 w/hotfixes) to another in the pool (same hardware spec / XenServer etc.) The domU's clock got advanced by a number of seconds: " Me: Tue Nov 3 09:55:52 GMT 2015 Them: Tue Nov 3 09:55:52 GMT 2015 [Migrate 'Me' Happens Now] Me: Tue Nov 3 09:56:02 GMT 2015 Them: Tue Nov 3 09:55:58 GMT 2015 Me: Tue Nov 3 09:56:06 GMT 2015 Them: Tue Nov 3 09:55:59 GMT 2015 Me: Tue Nov 3 09:56:07 GMT 2015 Them: Tue Nov 3 09:56:00 GMT 2015 Me: Tue Nov 3 09:56:08 GMT 2015 Them: Tue Nov 3 09:56:01 GMT 2015 " So you can see during the migrate the 'Me' (domU being moved) clock picks up 3 seconds, then another 4 seconds to make it 'ahead' 7 seconds in total - at which point it stabilises). It stays this way then - which is enough to cause NTP to "give up" trying to bring that back into alignment. > http://xenbits.xen.org/gitweb/?p=xen.git;a=commit;h=f8e8fd56bd7d5675e8331 > b4ec74bae76c9dbf24e > http://xenbits.xen.org/gitweb/?p=xen.git;a=commit;h=32c864a35ece2c24a336d > 183869a546798a4b241 Are either of those fixes likely to cure this? Thanks, -Karl