I believe this link might be helpful. Good luck.
Excerpt from link:
Allows the admin to define a special (isolated) set of images and a special (isolated) set of hosts, such that the isolated images can only run on the isolated hosts, and the isolated hosts can only run isolated images. The flag restrict_isolated_hosts_to_isolated_images can be used to force isolated hosts to only run isolated images.
The admin must specify the isolated set of images and hosts in the nova.conf file using the isolated_hosts and isolated_images configuration options. For example:
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isolated_hosts = server1, server2
isolated_images = 342b492c-128f-4a42-8d3a-c5088cf27d13, ebd267a6-ca86-4d6c-9a0e-bd132d6b7d09
http://docs.openstack.org/juno/config...