root@controller:~# nova service-list
+----+------------------+------------+----------+----------+-------+----------------------------+-----------------+
| Id | Binary           | Host       | Zone     | Status   | State | Updated_at                 | Disabled Reason |
+----+------------------+------------+----------+----------+-------+----------------------------+-----------------+
| 1  | nova-cert        | controller | internal | enabled  | up    | 2015-10-13T08:28:35.000000 | -               |
| 2  | nova-consoleauth | controller | internal | enabled  | up    | 2015-10-13T08:28:36.000000 | -               |
| 3  | nova-scheduler   | controller | internal | enabled  | up    | 2015-10-13T08:28:38.000000 | -               |
| 4  | nova-conductor   | controller | internal | enabled  | up    | 2015-10-13T08:28:36.000000 | -               |
| 7  | nova-compute     | compute2   | nova     | enabled  | up    | 2015-10-13T08:28:36.000000 | -               |
| 8  | nova-compute     | compute3   | nova     | enabled  | up    | 2015-10-13T08:28:40.000000 | -               |
| 9  | nova-compute     | compute1   | nova     | disabled | up    | 2015-10-13T08:28:37.000000 | -               |
+----+------------------+------------+----------+----------+-------+----------------------------+-----------------+
:: disabled --> enable 
usage: nova service-enable <hostname> <binary>
root@controller:~# nova service-enable  compute1 nova-compute
+----------+--------------+---------+
| Host     | Binary       | Status  |
+----------+--------------+---------+
| compute1 | nova-compute | enabled |
+----------+--------------+---------+
root@controller:~# nova service-disable  compute1 nova-compute
+----------+--------------+----------+
| Host     | Binary       | Status   |
+----------+--------------+----------+
| compute1 | nova-compute | disabled |
+----------+--------------+----------+