[libvirt-users] concurrent migration of several domains rarely fails

[Jim Fehlig]

On 12/10/18 5:46 AM, Lentes, Bernd wrote:
 > Hi Jim,
 >

Hi Bernd,

I was doing some mail housekeeping and realized I never responded to this 
message. Apologies for the long delay.

> Unfortunately not.
> 
> I have some more questions, maybe you can help me a bit.
> I found http://epic-alfa.kavli.tudelft.nl/share/doc/libvirt-devel-0.10.2/migration.html , which is
> quite interesting.

The canonical location of that doc is the libvirt website :-)

https://libvirt.org/migration.html

> When i migrate with virsh, i use:
> virsh --connect=qemu:///system migrate --verbose --live  domain qemu+ssh://ha-idg-1/system
> 
> When pacemaker migrates, it creates this sequence:
> virsh --connect=qemu:///system --quiet migrate --live  domain qemu+ssh://ha-idg-1/system
> which is quite the same.
> Do i understand the webpage correctly, is this a "Native migration, client to two libvirtd servers" ?

Yes, that is correct.

> Furthermore the document says:
> "To force migration over an alternate network interface the optional hypervisor specific URI must be provided".
> 
> I have both hosts also connected directly to each other with a bonding device using round-robin, and an internal ip (192.168.100.xx).
> When i want to use this device, which is maybe a bit faster and more secure (directly connected), how do i have to specify that ?

By using the 'migrateuri' parameter. See 'migrate' section of virsh man page for 
more details.

> virsh --connect=qemu:///system --quiet migrate --live  domain qemu+ssh://ha-idg-1/system tcp://192.168.100.xx

This example looks correct, where the 'tcp://192.168.100.xx' part is the migrateuri.

> Does it have to be the ip from the source or the destination ? Does the source then use automatically use
> also its device with 192.168.100.xx ?

It is the address of the destination. The destination will select a port if not 
specified, open a socket for the incoming migration, and provide the 
address/port to the source so it can connect and send the migration stream.

Note that /etc/libvirt/qemu.conf contains some knobs for controlling default 
migration settings in the qemu driver.

Regards,
Jim