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Re: [Xen-users] Live migration: 2500ms downtime
- To: "Luciano Rocha" <strange@xxxxxxxxxxxxx>
- From: "Marconi Rivello" <marconirivello@xxxxxxxxx>
- Date: Sat, 11 Aug 2007 00:57:48 -0300
- Cc: xen-users@xxxxxxxxxxxxxxxxxxx
- Delivery-date: Fri, 10 Aug 2007 20:58:17 -0700
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On 8/10/07, Luciano Rocha <strange@xxxxxxxxxxxxx> wrote:
On Fri, Aug 10, 2007 at 02:18:53PM -0300, Marconi Rivello wrote: > Hi, Luciano. > > On 8/10/07, Luciano Rocha <strange@xxxxxxxxxxxxx> wrote: > >
> > On Fri, Aug 10, 2007 at 12:42:08PM -0300, Marconi Rivello wrote: > > > Another issue that I described on a previous email (which, > > unfortunately, > > > didn't get any replies) is that this downtime increases to more than 20
> > > seconds if I set the domU's memory to 512MB (the maxmem set is 1024MB). > > I > > > repeated the test successively, from one side to the other, with mem set > > to > > > 512 and 1024, and the result was always the same. Around 3s with mem =
> > > maxmem, and around 24s with mem=512 and maxmem=1024. > > > > > > > You are using the option --live to migrate, aren't you? > > > Yes, I am. :)
Oh. Well, then, could you try without? :) I could, but what I'm whining :) about is to have a period of unresponsiveness of a couple of seconds, instead of a tenth of a second. If I do a stop-copy-restart migration it will be even longer.
Also, try the reverse. Ping an outside host in the domU.
I will. In fact, I will try all the monitoring suggestions (from you and the others). Inside domU, outside, third machine, ICMP, ARP...
> Even if I weren't, it would make sense to expect a lower downtime (or the > same downtime) by reducing the domU memory. But it takes longer if I reduce > the domU's memory.
That is odd. Is the Dom0 memory the same (ie., fixed)?
> Would you happen to have any ideas on why it behaves like that?
No idea. I might expect a longer migration time for a machine with a very active working set, but not a much longer downtime. That should be
only a freeze, final sync, and resume on the other side.
-- lfr 0/0
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I would like to thank everyone who contributed with ideas. It was very helpful. Unfortunately, I will be gone for the next week on a training, and will only be able to further investigate when I get back to work. When I do, I will do some more tests and post what I find out or not.
Thanks again, Marconi.
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