On 04/03/2014 05:48 PM, Jay Pipes wrote:
On Mon, 2014-03-31 at 17:11 +0800, Jay Lau wrote:
Hi,
Currently with VMWare VCDriver, one nova compute can manage multiple
clusters/RPs, this caused cluster admin cannot do live migration
between clusters/PRs if those clusters/PRs managed by one nova compute
as the current live migration logic request at least two nova
computes.
A bug [1] was also filed to trace VMWare live migration issue.
I'm now trying the following solution to see if it is acceptable for a
fix, the fix wants enable live migration with one nova compute:
1) When live migration check if host are same, check both host and
node for the VM instance.
2) When nova scheduler select destination for live migration, the live
migration task should put (host, node) to attempted hosts.
3) Nova scheduler needs to be enhanced to support ignored_nodes.
4) nova compute need to be enhanced to check host and node when doing
live migration.
What precisely is the point of "live migrating" an instance to the exact
same host as it is already on? The failure domain is the host, so moving
the instance from one "cluster" to another, but on the same host is kind
of a silly use case IMO.
Here is where precise definitions of "compute node",
"OS-EXT-SRV-ATTR:host", and "OS-EXT-SRV-ATTR:hypervisor_hostname", and
"host" as understood by novaclient would be nice.
Currently the "nova live-migration" command takes a "host" argument.
It's not clear which of the above this corresponds to.
My understanding is that one nova-compute process can manage multiple
VMWare physical hosts. So it could make sense to support live migration
between separate VMWare hosts even if they're managed by a single
nova-compute process.
Chris
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