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Re: [Xen-API] [XCP-1.6-BETA] SXM migration - ping timeouts

  • To: xen-api@xxxxxxxxxxxxx
  • From: George Shuklin <george.shuklin@xxxxxxxxx>
  • Date: Wed, 10 Oct 2012 03:09:23 +0400
  • Delivery-date: Tue, 09 Oct 2012 23:09:46 +0000
  • List-id: User and development list for XCP and XAPI <xen-api.lists.xen.org>

can't believe that.

Or you just use different kernels, or it not related to to 'guest tools' shell script.

10.10.2012 01:41, Burnie ÐÐÑÐÑ:
On 10/09/2012 10:39 PM, Vidar Normann wrote:
Actually, I believe this is because it uses gratuitous arp
to let the switch(es) the Xen hosts are connected to become aware that
the VM has moved.

That makes sense. Seems some arp tables (at the switch?) isn't updated
very quickly unless xs-tools is installed. And without network traffic
or link down/up, I guess linux doesn't send arp messages by itself.

Trying to ping from the vm itself during the migration seems to be
a "workaround".

On Oct 9, 2012 10:33 PM, "George Shuklin" <george.shuklin@xxxxxxxxx
<mailto:george.shuklin@xxxxxxxxx>> wrote:

It's really strange. xs tools for pv-domain is just simple shell
script to report vm internals back to XCP.

You can fake it presence with this script (run on host where VM

But behavior is really funny. May be PV presence cause live
migration and 'no guest tools' cause nomal migration (with pause and
without iterative incremental memory transfer)?

On 09.10.2012 23:23, Burnie wrote:

When migrating a VM from one standalone server to another, I noticed
that there's a huge gain in making sure the VM has xs-tools

VM: Centos 6.3 x86_64 - PV

- with xs-tools installed:
206 packets transmitted, 205 received, 0% packet loss, time 205680ms
rtt min/avg/max/mdev = 0.204/48.439/197.497/78.066 ms

- without xs-tools installed:
209 packets transmitted, 157 received, 24% packet loss, time
rtt min/avg/max/mdev = 0.217/66.975/196.220/84.136 ms

In both cases the VM seems to appear in XC within 1-2 seconds on the
new server, but without xs-tools, it doesn't seem to do any

I dont know if this is normal or not, but I guess it has
something to
do with some optimized drivers/modules?

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