Improve speed of Glance-vCenter interaction

[Andrey Danin]

Related bugs:
[0] https://bugs.launchpad.net/fuel/6.0.x/+bug/1316377
[1] https://bugs.launchpad.net/fuel/+bug/1370672
[2] https://bugs.launchpad.net/nova/+bug/1278690

As it was mentioned in [1], speed of copying of images between vCenter and non-VMDK Glance backends can be dramatically low. VMDK backend for Glance can fix this problem, but this approach will be unuseful in case of multihypervisor environment. So it would be nice to find out a way to improve speed for nonVMDK backends to let us use them for such environment.

[Andrey Danin (gcon-monolake)]

An interaction between Glance and vCenter in case of vCenter datastore backend was fixed in vCenter 5.5u2 update https://www.vmware.com/support/vsphere5/doc/vsphere-vcenter-server-55u2-release-notes.html

Regardless of what Glance backend is used, there is still two copying processes occurs: from Glance backend (local file system, Swift, Ceph, or vCenter datastore) to Nova-compute service via HTTP connection to Glance API, and from Nova-compute to a particular ESXi node via vSphere API connection. And both data transfers are running simultaneously. So, there is no way to significantly increase speed with such architecture.

But there is a blueprint about reusing vCenter Templates as a Glance images which prevents of copying of data to/from Nova-compute service. https://blueprints.launchpad.net/glance/+spec/hypervisor-templates-as-glance-images

So, let close this bug.