I am usually losing 1 ping for a big DomU (8-24 GB) unless the memory is
heavily actively used. In that case it is about 5 pings.
But I have implemented a work-around script which continually runs ping
and flush ARP cache every 0.2s - in DomU, without it the times were
around 20 pings like you said.
Moreover, as to the problem with time changing abruptly during live
migration, I recommend disabling ntpd just before migrating the domain
and re-enabling it after the migration. Otherwise a kernel panic occurs
on any subsequent ntpd shutdown... At least on my machines.
Regards,
Daniel
-----Original Message-----
From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED] On Behalf Of Marc Grimme
Sent: Tuesday, July 15, 2008 3:15 PM
To: Red Hat Enterprise Linux 5 (Tikanga) discussion mailing-list
Subject: Re: [rhelv5-list] Ping fails after Xen live migration
You should also read the following bugzillas:
https://bugzilla.redhat.com/show_bug.cgi?id=426861
http://bugzilla.xensource.com/bugzilla/show_bug.cgi?id=1282
They describe the same problem but recomment to set echo 1 >
/proc/sys/xen/independent_wallclock
on all dom0/Us. That did the trick for me.
Do you have any experiances in times the DomU is unreachable during
livemig (for example when looking at the network).
Depending on RAM we are loosing 20 Pings for 6GB RAM in DomU. I thinks
this is very much isn't it?
Thanks Marc.
On Saturday 12 July 2008 00:23:30 Rich Graves wrote:
> I think this is just a clock issue. Pings include timestamps and
> sequence numbers, and /proc/sys/net/ipv4/icmp_ratelimit does as the
name suggests.
>
> On the domU guest, echo 1 > /proc/sys/xen/independent_wallclock
>
> Do the live migration
>
> Then echo 0 > /proc/sys/xen/independent_wallclock
>
> I bet your clock and ping issues will both be resolved.
>
> Not yet tested (by me): does setting independent_wallclock on the
> dom0's do anything? That would be nice, because then you wouldn't have
> to take the time to ssh to guests before live migrates. (Anyone else
> have a good workaround? Is there any way to give user-space a hint
> that the kernel is starting a live migrate?)
>
> Frequently suggested but not desired (by me): use
> independent_wallclock all the time, and run NTP in each domU. -- Rich
> Graves http://claimid.com/rcgraves Carleton.edu Sr UNIX and Security
> Admin
> CMC135: 507-646-7079 Cell: 952-292-6529
>
> _______________________________________________
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--
Gruss / Regards,
Marc Grimme
Phone: +49-89 452 3538-14
http://www.atix.de/ http://www.open-sharedroot.org/
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