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

[Burnie <burnie@xxxxxx>]

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
>     resides):
>     http://wiki.xensource.com/__wiki/XAPI_fake_presence_of_PV___drivers
>     <http://wiki.xensource.com/wiki/XAPI_fake_presence_of_PV_drivers>
>
>     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
>         installed:
>
>         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
>         208432ms
>         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
>         networking.
>
>         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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--
Bernt  'Burnie'  Pettersen  ///  DoD#2345
<E-mail:burnie@xxxxxx>     ///  <URL:http://burnie.sh/>
       - Creative brains need creative workhours! -

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