Date: Tue, 03 Nov 2015 10:03:50 +0000 From: Karl Pielorz <kpielorz_lst@tdx.co.uk> To: =?UTF-8?Q?Roger_Pau_Monn=C3=A9?= <roger.pau@citrix.com>, 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>
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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
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