关于实例创建失败的问题，提示model server went away

创建实例时，在nova-cert.log，nova-conductor.log，nova-consoleauth.log，nova-scheduler.log这四个日志文件中提示相同的错误如下：
2016-01-09 12:13:12.026 1231 ERROR nova.servicegroup.drivers.db [-] Recovered model server connection!
2016-01-09 12:14:02.457 1231 ERROR nova.servicegroup.drivers.db [-] model server went away
2016-01-09 12:14:02.457 1231 TRACE nova.servicegroup.drivers.db Traceback (most recent call last):
2016-01-09 12:14:02.457 1231 TRACE nova.servicegroup.drivers.db File "/usr/lib/python2.7/dist-packages/nova/servicegroup/drivers/db.py", line 99, in _report_state
2016-01-09 12:14:02.457 1231 TRACE nova.servicegroup.drivers.db    service.service_ref, state_catalog)
2016-01-09 12:14:02.457 1231 TRACE nova.servicegroup.drivers.db File "/usr/lib/python2.7/dist-packages/nova/conductor/api.py", line 180, in service_update
2016-01-09 12:14:02.457 1231 TRACE nova.servicegroup.drivers.db    return self._manager.service_update(context, service, values)
2016-01-09 12:14:02.457 1231 TRACE nova.servicegroup.drivers.db File "/usr/lib/python2.7/dist-packages/nova/utils.py", line 973, in wrapper
2016-01-09 12:14:02.457 1231 TRACE nova.servicegroup.drivers.db    return func(*args, **kwargs)
2016-01-09 12:14:02.457 1231 TRACE nova.servicegroup.drivers.db File "/usr/lib/python2.7/dist-packages/oslo/messaging/rpc/server.py", line 139, in inner
2016-01-09 12:14:02.457 1231 TRACE nova.servicegroup.drivers.db    return func(*args, **kwargs)
2016-01-09 12:14:02.457 1231 TRACE nova.servicegroup.drivers.db File "/usr/lib/python2.7/dist-packages/nova/conductor/manager.py", line 320, in service_update
2016-01-09 12:14:02.457 1231 TRACE nova.servicegroup.drivers.db    svc = self.db.service_update(context,service['id'], values)
2016-01-09 12:14:02.457 1231 TRACE nova.servicegroup.drivers.db File "/usr/lib/python2.7/dist-packages//nova/db/api.py", line 150, in service_update
2016-01-09 12:14:02.457 1231 TRACE nova.servicegroup.drivers.db    return IMPL.service_update(context, service_id, values)
2016-01-09 12:14:02.457 1231 TRACE nova.servicegroup.drivers.db File "/usr/lib/python2.7/dist-packages/nova/db/sqlalchemy/api.py", line 125, in wrapper
2016-01-09 12:14:02.457 1231 TRACE nova.servicegroup.drivers.db    return f(*args, **kwargs)
2016-01-09 12:14:02.457 1231 TRACE nova.servicegroup.drivers.db File "/usr/lib/python2.7/dist-packages/nova/db/sqlalchemy/api.py", line 181, in wrapped
2016-01-09 12:14:02.457 1231 TRACE nova.servicegroup.drivers.db    return f(*args, **kwargs)
2016-01-09 12:14:02.457 1231 TRACE nova.servicegroup.drivers.db File "/usr/lib/python2.7/dist-packages/nova/db/sqlalchemy/api.py", line 525, in service_update
2016-01-09 12:14:02.457 1231 TRACE nova.servicegroup.drivers.db    service_ref.update(values)
2016-01-09 12:14:02.457 1231 TRACE nova.servicegroup.drivers.db File "/usr/lib/python2.7/dist-packages/sqlalchemy/orm/session.py", line 470, in __exit__
2016-01-09 12:14:02.457 1231 TRACE nova.servicegroup.drivers.db    self.rollback()
2016-01-09 12:14:02.457 1231 TRACE nova.servicegroup.drivers.db File "/usr/lib/python2.7/dist-packages/sqlalchemy/util/langhelpers.py", line 60, in __exit__
2016-01-09 12:14:02.457 1231 TRACE nova.servicegroup.drivers.db    compat.reraise(exc_type, exc_value, exc_tb)
2016-01-09 12:14:02.457 1231 TRACE nova.servicegroup.drivers.db File "/usr/lib/python2.7/dist-packages/sqlalchemy/orm/session.py", line 467, in __exit__
2016-01-09 12:14:02.457 1231 TRACE nova.servicegroup.drivers.db    self.commit()
2016-01-09 12:14:02.457 1231 TRACE nova.servicegroup.drivers.db    return meth(self, multiparams, params)
2016-01-09 12:14:02.457 1231 TRACE nova.servicegroup.drivers.db File "/usr/lib/python2.7/dist-packages/sqlalchemy/sql/elements.py", line 321, in _execute_on_connection
2016-01-09 12:14:02.457 1231 TRACE nova.servicegroup.drivers.db    return connection._execute_clauseelement(self, multiparams, params)
2016-01-09 12:14:02.457 1231 TRACE nova.servicegroup.drivers.db File "/usr/lib/python2.7/dist-packages/sqlalchemy/engine/base.py", line 826, in _execute_clauseelement
2016-01-09 12:14:02.457 1231 TRACE nova.servicegroup.drivers.db    compiled_sql, distilled_params
2016-01-09 12:14:02.457 1231 TRACE nova.servicegroup.drivers.db File "/usr/lib/python2.7/dist-packages/sqlalchemy/engine/base.py", line 958, in _execute_context
2016-01-09 12:14:02.457 1231 TRACE nova.servicegroup.drivers.db    context)
2016-01-09 12:14:02.457 1231 TRACE nova.servicegroup.drivers.db File "/usr/lib/python2.7/dist-packages/sqlalchemy/engine/base.py", line 1156, in _handle_dbapi_exception
2016-01-09 12:14:02.457 1231 TRACE nova.servicegroup.drivers.db    util.raise_from_cause(newraise, exc_info)
2016-01-09 12:14:02.457 1231 TRACE nova.servicegroup.drivers.db File "/usr/lib/python2.7/dist-packages/sqlalchemy/util/compat.py", line 199, in raise_from_cause
2016-01-09 12:14:02.457 1231 TRACE nova.servicegroup.drivers.db    reraise(type(exception), exception, tb=exc_tb)
2016-01-09 12:14:02.457 1231 TRACE nova.servicegroup.drivers.db File "/usr/lib/python2.7/dist-packages/sqlalchemy/engine/base.py", line 951, in _execute_context
2016-01-09 12:14:02.457 1231 TRACE nova.servicegroup.drivers.db    context)
2016-01-09 12:14:02.457 1231 TRACE nova.servicegroup.drivers.db File "/usr/lib/python2.7/dist-packages/sqlalchemy/engine/default.py", line 436, in do_execute
2016-01-09 12:14:02.457 1231 TRACE nova.servicegroup.drivers.db    cursor.execute(statement, parameters)
2016-01-09 12:14:02.457 1231 TRACE nova.servicegroup.drivers.db OperationalError: (OperationalError) database is locked u'UPDATE services SET updated_at=?, report_count=? WHERE services.id = ?' ('2016-0109 04:14:02.456764', 6524, 2)
2016-01-09 12:14:02.457 1231 TRACE nova.servicegroup.drivers.db
请大家帮忙看下，谢谢！

创建实例时错误提示如图