Migration and Node parameter

Migration and Node parameter

[Stefan de Konink]

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    def domain_migrate(self, domid, dst, live=False, port=0, node=-1,
ssl=None):
        """Start domain migration.

        @param domid: Domain ID or Name
        @type domid: int or string.
        @param dst: Destination IP address
        @type dst: string
        @keyword live: Live migration
        @type live: bool
        @keyword port: relocation port on destination
        @type port: int
        @keyword node: use node number for target
        @type node: int
        @keyword ssl: use ssl connection
        @type ssl: bool
        @rtype: None
        @raise XendError: Failed to migrate
        @raise XendInvalidDomain: Domain is not valid


What does the node parameter do in this context?


Stefan
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Re: Migration and Node parameter

[Andre Przywara]

Stefan de Konink wrote:
>     def domain_migrate(self, domid, dst, live=False, port=0, node=-1,
> ssl=None):
>         """Start domain migration.
> ...
>         @keyword node: use node number for target
>         @type node: int
 > ...
> What does the node parameter do in this context?

This means the NUMA node the new guest should be created on. Newer Xen 
versions create guests on a single node and choose the least used one. 
If later the system load changes, it can become imbalanced in respect to 
equal load on all nodes. In this situation you can manually move a guest 
to another NUMA node. (NUMA literature often uses the term "NUMA domain" 
instead of node, but for obvious reason I try to avoid this term in Xen)
Using localhost migration for this purpose isn't the smartest solution, 
but was fairly easy to implement ... and works.
See unstable c/s 17148 for the code.

Regards,
Andre.

-- 
Andre Przywara
AMD-Operating System Research Center (OSRC), Dresden, Germany
Tel: +49 351 277-84917
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