[Openstack] Fwd: nova instance

Markus Zoeller mzoeller at de.ibm.com
Mon Aug 25 11:49:03 UTC 2014

javed alam <javedamar at gmail.com> wrote on 08/23/2014 02:39:38 PM:

> From: javed alam <javedamar at gmail.com>
> To: openstack <openstack at lists.openstack.org>, Masoom Alam 
> <masoom.alam at gmail.com>
> Date: 08/23/2014 02:49 PM
> Subject: [Openstack] Fwd: nova instance
> ...
> "Error: Failed to launch instance "nova_testing": Please try again 
> later [Error: No valid host was found. ]. "
> ...
> i m even unable to find the log files.
Hi Javed,

the error "no valid host found" is thrown by the `nova-scheduler` 
service (see [1] for details). 

Depending on your testing environment you have to check different things:

1) An "All-In-One" DevStack[2] setup:
   * check your `local.conf` file in your devstack folder. There should 
     be the following lines: 
   * The log of the scheduler is then available at:
   * The scheduler log should contain more information about the cause
Afaik the changes will be applied when the services are restarted. You 
can either execute the DevStack scripts `unstack.sh` and `stack.sh` or
use the screen tool (see [4]).

2) A dedicated controller node:
The default folder for nova logs is `/var/log/nova`. The scheduler log 
should be there. Maybe you have to turn on debugging in the file 
`/etc/nova/nova.conf` in the line `debug=true` and `verbose=true`.

More infos about working with logs can be found at [3].

[1] OpenStack configuration reference; Juno Release (draft); 
    Section "Scheduling" 

[2] DevStack; http://devstack.org/guides/single-machine.html 
[3] OpenStack Cloud Administrator Guide; Section "Manage Logs";
[4] IBM Developer Works; 2013-12-06; Restart services of devstack based 

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