[Openstack] Compute Node Down!

Vishvananda Ishaya vishvananda at gmail.com
Thu Sep 20 03:50:14 UTC 2012


rescue does not bring back nodes from dead hosts. It reboots the instance with a fresh copy of the image it booted with as the base drive and attaches the current drive as a second drive so you can mount it and fix things. Unrescue switches back to the original drive after you have made your repairs.

Vish

On Sep 19, 2012, at 7:13 PM, Sam Stoelinga <sammiestoel at gmail.com> wrote:

> Hi Ale,
> 
> It's the first time I see nova rescue, maybe this should be somewhere else in the documentation. Maybe the part related to migration, that's where I looked and tried.
> 
> I first tried to do migration of the VM on a dead host, but that didn't work then after searching I stumbled upon this patch to enable the functionality to move VMs from a dead host:
> https://review.openstack.org/#/c/11086/12
> But it wasn't available for Essex, and won't be in Folsom either. So I thought this functionality was not there yet either. Searched for ours documentation and google, but never saw anything about rescue.
> Is the functionality the same as the above patch? I looked at the code, and the code seems much smaller. The above patch seems to do more cleaning up also.
> 
> Because I didn't know about nova rescue I already copied the patch to Essex successfully, but maybe it's safe to use nova rescue.
> This is the evacuate patch for stable essex: https://review.openstack.org/#/c/13282/
> 
> Do I understand right that this is the workflow: 
> nova rescue instance1
> Look if the state changed to RESCUED
> if it's rescued do a nova unrescue instance1
> which cleans up the resources used for rescuing and changes the state back to ACTIVE on the vm?
> 
> Thanks a lot, sure is helpful.
> 
> Sam
> 
> On Wed, Sep 19, 2012 at 9:12 PM, Alejandro Comisario <alejandro.comisario at mercadolibre.com> wrote:
> if you are on essex, you can issue a "nova rescue", if in cactus, you have to manipulate the "instances" table to tell where the new instance will be running, and then from the new compute node issue a :
> 
> virsh define /path/to/XML
> virsh start instance_name
> 
> From that moment, you can manage the instance using euca / nova
> 
> Ale
> 
> On Wed, Sep 19, 2012 at 4:03 AM, Wolfgang Hennerbichler <wolfgang.hennerbichler at risc-software.at> wrote:
> Hello Folks,
> 
> Although it seems a pretty straightforward scenario I have a hard time finding documentation on this.
> One of my compute nodes broke down. All the instances are on shared storage, so no troubles here, but I don't know how to tell openstack that the VM should be deployed on another compute node. I tried fiddling around in the mysql-db with no success.
> Any help is really appreciated.
> 
> Wolfgang
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