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Follow up:

I ran another test with the external cinder-volume as storage backend  
for my instances' images. Since cinder tried to create a new target,  
this section was commented out in the scst.py to see how far I can  
get. This leads to a new error, but not on the cinder node. It's  
something that's not implemented yet for xen, IIUC.
So basically, I need to tell cinder somehow to not create a new target  
but use the existing for that specific instance. But where do I need  
to do that, which option is it in what config file?

Any help is appreciated!

Regards,
Eugen


Zitat von Eugen Block <eblock at nde.ag>:

> Hi everyone,
>
> I have successfully deployed a 3 node environment (1 control, 2  
> compute nodes, all of them running with openSUSE Leap 42.1)  
> according to the docs. I also added an external storage node as a  
> cinder-volume to store the instance images on a SAN-Server, not in  
> local files. That works just fine, until I try to (live-)migrate an  
> instance.
>
> The instances was created by
>
> nova boot --block-device  
> source=image,id=24939ebe-6201-48f9-bb0d-5c207d94cea2,dest=volume,size=1,shutdown=remove,bootindex=0 --nic net-id=1940e2f7-ec41-4d2f-b531-11e8d229145d --flavor 1  
> VMfromVol
>
> Running "nova live-migration VMfromVol" leads to this error in  
> cinder-volume.log:
> ---cut here---
> Stdout: u'Unexpected error while running command.
> Command: scstadmin -open_dev disk1 -handler vdisk_fileio -attributes  
> filename=/dev/ndesan03/volume-a3a78f9d-39b5-46af-aea8-d310a22795ff
> Exit code: 1
> Stdout: u"\\nCollecting current configuration: done.\\n\\n\\n->  
> Making requested changes.\\n\\t-> Opening device \'disk1\' using  
> handler \'vdisk_fileio\': done.\\n\\n\\nFATAL: Received the  
> following error:\\n\\n\\tDevice already exists.\\n\\n"\nStderr: u\'\''
>
> ERROR cinder.volume.manager ISCSITargetHelperCommandFailed: Failed  
> to add device to SCST handler
> ---cut here---
>
> nova-compute.log only reports:
>
> Remote error: ClientException The server has either erred or is  
> incapable of performing the requested operation.
>
> and on the other compute node:
>
> ClientException: The server has either erred or is incapable of  
> performing the requested operation.
>
> So to summarize: there is an existing iscsi target on one compute  
> node for a running instance. The command "nova live-migration  
> <server> <host>" triggers cinder to create another iscsi target for  
> the other compute node, but with the same volume label, which  
> already exists and the operation fails. Is there something I'm  
> missing in the config files? How can I ensure that the other compute  
> node only logs in to the same target and doesn't create a new export?
>
> I would really appreciate any help! If you need any other  
> information about my configs or the whole stack traces from  
> nova-compute.log and cinder-volume.log, please let me know!
>
> Best regards,
> Eugen
>
> -- 
> Eugen Block                             voice   : +49-40-559 51 75
> NDE Netzdesign und -entwicklung AG      fax     : +49-40-559 51 77
> Postfach 61 03 15
> D-22423 Hamburg                         e-mail  : eblock at nde.ag
>
>         Vorsitzende des Aufsichtsrates: Angelika Mozdzen
>           Sitz und Registergericht: Hamburg, HRB 90934
>                   Vorstand: Jens-U. Mozdzen
>                    USt-IdNr. DE 814 013 983
>
>
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-- 
Eugen Block                             voice   : +49-40-559 51 75
NDE Netzdesign und -entwicklung AG      fax     : +49-40-559 51 77
Postfach 61 03 15
D-22423 Hamburg                         e-mail  : eblock at nde.ag

         Vorsitzende des Aufsichtsrates: Angelika Mozdzen
           Sitz und Registergericht: Hamburg, HRB 90934
                   Vorstand: Jens-U. Mozdzen
                    USt-IdNr. DE 814 013 983