Hello, menu thanks for your reply.

I tried both post copy and converge but the live migrations is always very slow for applications servers like tomcat with java.

The very strange behaviour is that if I migrate from compute node A to compute node B it takes more than 20 minutes.

After that, if I migrate from compute B to compute A, it takes few seconds.

I do not know if its is because dirty memory iscleaned during the first live migration.

Live migration network si 10Gbs so I do not think the first live migration is affected by network performances.

Ignazio

Il giorno gio 4 ago 2022 alle ore 11:34 Fabian Zimmermann <dev.faz@gmail.com> ha scritto:

Hi,

take a look at:
https://docs.openstack.org/nova/latest/admin/configuring-migrations.html#advanced-configuration-for-kvm-and-qemu

esp. Auto-convergence and Post-copy

Fabian

Am Mi., 3. Aug. 2022 um 12:43 Uhr schrieb Ignazio Cassano
<ignaziocassano@gmail.com>:
>
> Hello All,
> I am looking for a solution to speed up live migration.
> Instances where ram is used heavily like java application servers, live migration take a long time (more than 20 minutes for 8GB ram instance) and converge mode is already set to True in nova.conf.
> I also tried with post_copy but it does not change.
> After the first live migration (very solow) if I try to migrate again it is very fast.
> I presume the first migration is slow because memory fragmentation when an instance is running on the same compute node for a long time.
> I am looking for a solution considering the on my computing node I can have
> a little ram overcommit. Any case I am increasing the number of compute nodes to reduce it.
> Thanks
> Ignazio
>