[root@controller nova]# su -s /bin/sh -c “nova-manage db sync” nova
/usr/lib/python2.7/site-packages/pymysql/cursors.py:170: Warning: (1831, u’Duplicate index block_device_mapping_instance_uuid_virtual_name_device_name_idx. This is deprecated and will be disallowed in a future release.‘)
result = self._query(query)
/usr/lib/python2.7/site-packages/pymysql/cursors.py:170: Warning: (1831, u’Duplicate index uniq_instances0uuid. This is deprecated and will be disallowed in a future release.’)
result = self._query(query)

根据提示：uuid重复了，这里算是警告信息把？不用管它也行，没有提示error
原因：这个警告表明在nova数据库中存在重复的索引。在未来的MariaDB版本中，这将是不允许的。为了解决这个问题，你需要删除重复的索引。以下是详细的步骤：

登录数据库：
选择 nova数据库
查询和删除：

MariaDB [nova]> SHOW INDEX FROM instances;
MariaDB [nova]> ALTER TABLE instances DROP INDEX uniq_instances0uuid;

删除后：
再次执行：

[root@controller nova]# su -s /bin/sh -c "nova-manage db sync" nova
MariaDB [(none)]> use nova;
MariaDB [nova]> SHOW INDEX FROM instances;