本人按照官方最新的安装文档安装测试环境，在完全照搬测试文档的情况下，居然也会报错，一紧。
在安装完NOVA之后，运行nova service-list进行测试，报错大概是：unable to establish connection to http://controller,就是无法建立到nova api的连接。
百度google一翻之后发现很多帖子都说的模糊。郁闷。
没办法，条件反射般看看cpu和内存，发现内存利用率很高，难道是内存不够吗？
抱着尝试的心态，关虚拟机，虚拟机内存到2G，开机测试。居然成功运行命令。可惜科和。
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root@openstack-controller:~# nova service-list
+----+------------------+----------------------+----------+---------+-------+----------------------------+-----------------+
| Id | Binary | Host | Zone | Status | State | Updated_at | Disabled Reason |
+----+------------------+----------------------+----------+---------+-------+----------------------------+-----------------+
| 1 | nova-cert | openstack-controller | internal | enabled | up | 2015-11-30T01:11:50.000000 | - |
| 2 | nova-consoleauth | openstack-controller | internal | enabled | up | 2015-11-30T01:11:50.000000 | - |
| 3 | nova-scheduler | openstack-controller | internal | enabled | up | 2015-11-30T01:11:51.000000 | - |
| 4 | nova-conductor | openstack-controller | internal | enabled | up | 2015-11-30T01:11:50.000000 | - |
| 5 | nova-compute | openstack-compute | nova | enabled | up | 2015-11-30T01:11:43.000000 | - |
+----+------------------+----------------------+----------+---------+-------+----------------------------+-----------------+
root@openstack-controller:~# free -m
total used free shared buffers cached
Mem: 2001 1542 459 0 20 205
-/+ buffers/cache: 1316 685
Swap: 507 0 507
root@openstack-controller:~#
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openstack- unable to establish connection to http://controller
原文地址：http://dogrider.blog.51cto.com/771879/1718043
