[Openstack] [cinder] live-migration of volume-backend instance fails

Eugen Block eblock at nde.ag
Tue Mar 1 15:43:56 UTC 2016


Thanks for your response!
Do you have more detailed information if SCST is not fully implemented  
using Xen and live-migration or is it a possible bug we could work on  
and maybe fix it? Or is it not designed to work that way? That would  
be interesting...


Zitat von "Griffith, John" <John.Griffith at netapp.com>:

> It’s not a config option.  It’s the way the SCST target driver works  
> unfortunately.  You’re using SCST and Xen, unfortunately neither of  
> which are configurations that I have any real experience with  
> especially when it comes to live-migration.
>
>> On Mar 1, 2016, at 03:35, Eugen Block <eblock at nde.ag> wrote:
>>
>> 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
>>>
>>>
>>> _______________________________________________
>>> Mailing list: http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack
>>> Post to     : openstack at lists.openstack.org
>>> Unsubscribe : http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack
>>
>>
>>
>> --
>> 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
>>
>>
>> _______________________________________________
>> Mailing list: http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack
>> Post to     : openstack at lists.openstack.org
>> Unsubscribe : http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack



-- 
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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