[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: [Xen-users] Xen live migration dom0 memory

On 07/01/2015 04:30 PM, Ian Campbell wrote:
On Wed, 2015-07-01 at 16:20 +0200, Epiontis IT wrote:

I'm new to XEN live migration. I have a question regarding XEN memory
management while doing a vm live migration. I observed that migrating a
vm on XEN 4.5.1 and Linux Kernel 4.1.0 requires the dom0 on the target
machine to have memory available that is the size of the memory
allocated to the vm (2G). Since I follow "XEN best practices" and set
dom0_mem to 512M the target machine begins swapping out 2G to disk which
makes everything nearly unresponsive. Is this requirement for the dom0
memory size intended or might there be an issue with my setup?
I don't think you should need 2G dom0 memory, you should need 2G of free
host memory.

Perhaps something on your destination host is thinking it wants to
balloon dom0 down in order to make that free host memory available?


I started out with only one vm running on the sending host, none on the destination host. Both hosts have dom_0=512M and 32GB free memory for the vms, autoballooning=0 is set in xl.conf. As soon as I do a "xl migrate" the destination host begins swapping out 2GB to disk. In an earlier setup I had XEN 4.4.1 and Linux 3.18 running and never observed any swapping as far as I could tell. So from your comment I conclude that there is some problem with my setup and dom0 doesn't need the vm memory size available for doing the migration.


Alexander Hämmerle

Epiontis GmbH
Rudower Chaussee 29
12489 Berlin

Phone: +49 30 63923478
Fax:   +49 30 63923476
eMail: Alexander.Haemmerle@xxxxxxxxxxxx
WWW:   www.epiontis.com

Dr. Ulrich Hoffmüller
Sven Olek, PhD
Helge Riemer

Amtsgericht Charlottenburg
HRB 88858

Diese E-Mail könnte  vertrauliche und/oder rechtlich geschützte
Informationen enthalten. Falls Sie nicht der richtige Adressat sind oder
diese E-Mail irrtümlich erhalten haben, informieren Sie bitte sofort den
Absender und vernichten Sie diese Mail. Das unerlaubte Kopieren sowie
die unbefugte Weitergabe dieser Mail sind nicht erlaubt.

This e-mail may contain confidential and/or privileged information. If
you are not the intended recipient (or have received this e-mail in
error) please notify the sender immediately and destroy this e-mail. Any
unauthorised copying, disclosure or distribution of the material in this
e-mail is strictly forbidden.

Xen-users mailing list



Lists.xenproject.org is hosted with RackSpace, monitoring our
servers 24x7x365 and backed by RackSpace's Fanatical Support®.