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unable to resize instance

asked 2016-09-27 04:45:50 -0500

tong1125 gravatar image

I followed the latest installation guide ( ( to setup the openstack. everything works fine. Then I tried the resize feature. But the resize failed with the following error message:

ken@controller:~$ nova resize 2adbfad6-ae27-4af5-9596-3252044b9817 0 ERROR (BadRequest): No valid host was found. No valid host found for resize (HTTP 400) (Request-ID: req-38700377-8394-46b1-8f47-7e7c9c256929)

Then I checked the nova-api log and found the following message: ken@controller:/var/log/nova$ cat nova-conductor.log 2016-09-27 17:42:17.936 1154 WARNING nova.scheduler.utils [req-c3a3de80-ee69-41ff-819b-9577ecc3531b 7ea37408ad9f409f858116cebc5f84bc 260e011ff9c54f959a22410a032f7d6a - - -] Failed to compute_task_migrate_server: No valid host was found. There are not enough hosts available. Traceback (most recent call last):

File "/usr/lib/python2.7/dist-packages/oslo_messaging/rpc/", line 150, in inner return func(args, *kwargs)

File "/usr/lib/python2.7/dist-packages/nova/scheduler/", line 104, in select_destinations dests = self.driver.select_destinations(ctxt, spec_obj)

File "/usr/lib/python2.7/dist-packages/nova/scheduler/", line 74, in select_destinations raise exception.NoValidHost(reason=reason)

NoValidHost: No valid host was found. There are not enough hosts available.

Can anyone give me a hint to troubleshoot this issue?

BTW, glance/keystone/neutron are all installed in the control node.

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answered 2016-10-11 01:35:11 -0500

tong1125 gravatar image

It turns out "resize" is just kind of migration. So extra compute node is needed. After adding a second compute node. Resize works like a charm.

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BTW, in order to resize successfully, two compute hosts need to be "ssh" to each other without password.

tong1125 gravatar imagetong1125 ( 2016-10-11 01:36:05 -0500 )edit

answered 2017-02-09 19:05:04 -0500

Armyofevilrobots gravatar image

If you are running a single node OpenStack, you can still resize (and migrate will migrate back to the same host) by adding the following configuration option to your nova.conf:


Then restart your nova scheduler and services:

systemctl restart "openstack-nova-*"

You can now resize your instances on the same host.

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Asked: 2016-09-27 04:27:43 -0500

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Last updated: Oct 11 '16