[libvirt-users] using transport protocol in live migration

[Eric Blake]

On 04/12/2013 07:28 AM, digvijay chauhan wrote:
> Hello,
>         I am working on live migration of virtual machine using xen and
> kvm.If i use qemu+ssh:///system then is the transport protocol used during
> live migration tcp or ssh?I mean i want to evaluate the performance of
> transport protocil during live migration using wireshark and netperf
> tool,so using this command will show tcp performance?
> 
> Orelse i will have to use qemu+tcp:/// ?

I'd start by reading and understanding this page:
http://libvirt.org/migration.html

If you do native migration, then it uses whatever protocol the native
hypervisor uses (qemu only supports direct tcp), through a separate
port.  If you use tunnelled migration, then the migration is multiplexed
onto libvirt's connection (no additional open port required), and the
transport then depends on however you connected to libvirt (whether it
is straight TCP or whether it is using SSH depends on the URI of how you
connected).  Tunnelled migration is inherently slower, since there are
more copies involved - qemu -> libvirtd source -> libvirtd destination
-> qemu; compared to native migration of qemu -> qemu.  But it also
provides the possibility of SSH or TLS encryption, if you don't want
migration going across the wire unencrypted (since qemu does not yet
support encrypted migration natively).

-- 
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org

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