[openstack-dev] [nova] why is evacuate marked as missing for libvirt?
Daniel P. Berrange berrange at redhat.com wrote on 04/15/2015 11:35:39 AM: From: Daniel P. Berrange berrange at redhat.com To: OpenStack Development Mailing List (not for usage questions) openstack-dev at lists.openstack.org Date: 04/15/2015 11:42 AM Subject: Re: [openstack-dev] [nova] why is evacuate marked as missing for libvirt? On Tue, Apr 14, 2015 at 01:44:45PM -0400, Russell Bryant wrote: On 04/14/2015 12:22 PM, Matt Riedemann wrote: This came up in IRC this morning, but the hypervisor support matrix is listing evacuate as 'missing' for the libvirt driver: http://docs.openstack.org/developer/nova/support- matrix.html#operation_evacuate Does anyone know why that is? The rebuild method in the compute manager just re-uses other virt driver operations so by default it's implemented by all drivers. The only one that overrides rebuild for evacuate is the ironic driver. I think it's a case where there are a couple of different things referred to with 'evacuate'. I believe this was originally added to track something that was effectively XenServer specific and the description of the feature seems to reflect that. We've since added the more generic 'evacuate' API, so it's pretty confusing. It should probably be reworked to track which drivers work with the 'evacuate' API call, and perhaps have a different entry for whatever this different XenServer thing is (or was). Yep, if there's any mistakes or bizarre things in the support matrix just remember that the original wiki page had essentially zero information about what each feature item was referring to - just the two/three word feature name. When I turned it into formal docs I tried to add better explanations, but it is entirely possible my interpretations were wrong in places. So if in doubt assume the support matrix is wrong, and just send a review to update it to some saner state with better description of the feature. Pretty much all the features in the matrix could do with better explanations and/or being broken up into finer grained features - there's plenty of scope for people to submit patches to improve the granularity of items. I think that the confusion is caused by something called the host maintenance mode [1]. When this is enabled, an evacuate is triggered by the underlying hypervisor. This can mode can be set by the CLI [2] and is not implemented by the libvirt driver. The probably intented API for the feature evacuate is [3] which can be triggered via CLI with: * nova evacuate server * nova host-evacuate host * nova host-evacuate-live host The feature evacuate has hereby a dependency to live-migration. As the system z platform doesn't yet has [4] merged, evacuate is there partial [5] (TODO for me) whereas for x86 there should be complete. Please correct me if I'm wrong here. Unfortunately I couldn't find any tempest tests for the evacuate feature, so I tested in manually. [1] virt.driver.ComputeDriver.host_maintenance_mode(self, host, mode) https://github.com/openstack/nova/blob/2015.1.0rc1/nova/virt/driver.py#L1016 [2] Nova CLI; command nova host-update http://docs.openstack.org/cli-reference/content/novaclient_commands.html [3] nova.api.openstack.compute.contrib.evacuate https://github.com/openstack/nova/blob/2015.1.0rc1/nova/api/openstack/compute/contrib/evacuate.py [4] libvirt: handle NotSupportedError in compareCPU https://review.openstack.org/#/c/166130/ [5] Update hypervisor support matrix with column for kvm on system z https://review.openstack.org/#/c/172391/ Regards, Markus Zoeller (markus_z) Today the topic about evacuate and host maintenance mode came up again in the IRC nova channel. I'd like to try again to state how I understand it. At the end will be suggestions how this could be solved. CLI - API - Driver The mapping between the python-novaclient, the nova REST API and the nova.virt.driver looks like this: CLIAPI Driver ---- nova host-update hosts.pyhost_maintenance_mode() update()set_host_enabled() ---- nova evacuate evacuate.py rebuild() _evacuate() ---- nova host-evacuate evacuate.py rebuild() [calls API in a loop] _evacuate() ---- nova host-evacuate-liveadmin_actions.pylive_migration() [calls API in a loop] _migrate_live() ---- The CLI command nova host-update [1] calls the update
Re: [openstack-dev] [nova] why is evacuate marked as missing for libvirt?
Daniel P. Berrange berra...@redhat.com wrote on 04/15/2015 11:35:39 AM: From: Daniel P. Berrange berra...@redhat.com To: OpenStack Development Mailing List (not for usage questions) openstack-dev@lists.openstack.org Date: 04/15/2015 11:42 AM Subject: Re: [openstack-dev] [nova] why is evacuate marked as missing for libvirt? On Tue, Apr 14, 2015 at 01:44:45PM -0400, Russell Bryant wrote: On 04/14/2015 12:22 PM, Matt Riedemann wrote: This came up in IRC this morning, but the hypervisor support matrix is listing evacuate as 'missing' for the libvirt driver: http://docs.openstack.org/developer/nova/support- matrix.html#operation_evacuate Does anyone know why that is? The rebuild method in the compute manager just re-uses other virt driver operations so by default it's implemented by all drivers. The only one that overrides rebuild for evacuate is the ironic driver. I think it's a case where there are a couple of different things referred to with 'evacuate'. I believe this was originally added to track something that was effectively XenServer specific and the description of the feature seems to reflect that. We've since added the more generic 'evacuate' API, so it's pretty confusing. It should probably be reworked to track which drivers work with the 'evacuate' API call, and perhaps have a different entry for whatever this different XenServer thing is (or was). Yep, if there's any mistakes or bizarre things in the support matrix just remember that the original wiki page had essentially zero information about what each feature item was referring to - just the two/three word feature name. When I turned it into formal docs I tried to add better explanations, but it is entirely possible my interpretations were wrong in places. So if in doubt assume the support matrix is wrong, and just send a review to update it to some saner state with better description of the feature. Pretty much all the features in the matrix could do with better explanations and/or being broken up into finer grained features - there's plenty of scope for people to submit patches to improve the granularity of items. I think that the confusion is caused by something called the host maintenance mode [1]. When this is enabled, an evacuate is triggered by the underlying hypervisor. This can mode can be set by the CLI [2] and is not implemented by the libvirt driver. The probably intented API for the feature evacuate is [3] which can be triggered via CLI with: * nova evacuate server * nova host-evacuate host * nova host-evacuate-live host The feature evacuate has hereby a dependency to live-migration. As the system z platform doesn't yet has [4] merged, evacuate is there partial [5] (TODO for me) whereas for x86 there should be complete. Please correct me if I'm wrong here. Unfortunately I couldn't find any tempest tests for the evacuate feature, so I tested in manually. [1] virt.driver.ComputeDriver.host_maintenance_mode(self, host, mode) https://github.com/openstack/nova/blob/2015.1.0rc1/nova/virt/driver.py#L1016 [2] Nova CLI; command nova host-update http://docs.openstack.org/cli-reference/content/novaclient_commands.html [3] nova.api.openstack.compute.contrib.evacuate https://github.com/openstack/nova/blob/2015.1.0rc1/nova/api/openstack/compute/contrib/evacuate.py [4] libvirt: handle NotSupportedError in compareCPU https://review.openstack.org/#/c/166130/ [5] Update hypervisor support matrix with column for kvm on system z https://review.openstack.org/#/c/172391/ Regards, Markus Zoeller (markus_z) __ OpenStack Development Mailing List (not for usage questions) Unsubscribe: openstack-dev-requ...@lists.openstack.org?subject:unsubscribe http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-dev
Re: [openstack-dev] [nova] why is evacuate marked as missing for libvirt?
On Tue, Apr 14, 2015 at 01:44:45PM -0400, Russell Bryant wrote: On 04/14/2015 12:22 PM, Matt Riedemann wrote: This came up in IRC this morning, but the hypervisor support matrix is listing evacuate as 'missing' for the libvirt driver: http://docs.openstack.org/developer/nova/support-matrix.html#operation_evacuate Does anyone know why that is? The rebuild method in the compute manager just re-uses other virt driver operations so by default it's implemented by all drivers. The only one that overrides rebuild for evacuate is the ironic driver. I think it's a case where there are a couple of different things referred to with 'evacuate'. I believe this was originally added to track something that was effectively XenServer specific and the description of the feature seems to reflect that. We've since added the more generic 'evacuate' API, so it's pretty confusing. It should probably be reworked to track which drivers work with the 'evacuate' API call, and perhaps have a different entry for whatever this different XenServer thing is (or was). Yep, if there's any mistakes or bizarre things in the support matrix just remember that the original wiki page had essentially zero information about what each feature item was referring to - just the two/three word feature name. When I turned it into formal docs I tried to add better explanations, but it is entirely possible my interpretations were wrong in places. So if in doubt assume the support matrix is wrong, and just send a review to update it to some saner state with better description of the feature. Pretty much all the features in the matrix could do with better explanations and/or being broken up into finer grained features - there's plenty of scope for people to submit patches to improve the granularity of items. Regards, Daniel -- |: http://berrange.com -o-http://www.flickr.com/photos/dberrange/ :| |: http://libvirt.org -o- http://virt-manager.org :| |: http://autobuild.org -o- http://search.cpan.org/~danberr/ :| |: http://entangle-photo.org -o- http://live.gnome.org/gtk-vnc :| __ OpenStack Development Mailing List (not for usage questions) Unsubscribe: openstack-dev-requ...@lists.openstack.org?subject:unsubscribe http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-dev
[openstack-dev] [nova] why is evacuate marked as missing for libvirt?
This came up in IRC this morning, but the hypervisor support matrix is listing evacuate as 'missing' for the libvirt driver: http://docs.openstack.org/developer/nova/support-matrix.html#operation_evacuate Does anyone know why that is? The rebuild method in the compute manager just re-uses other virt driver operations so by default it's implemented by all drivers. The only one that overrides rebuild for evacuate is the ironic driver. -- Thanks, Matt Riedemann __ OpenStack Development Mailing List (not for usage questions) Unsubscribe: openstack-dev-requ...@lists.openstack.org?subject:unsubscribe http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-dev
Re: [openstack-dev] [nova] why is evacuate marked as missing for libvirt?
On 04/14/2015 12:22 PM, Matt Riedemann wrote: This came up in IRC this morning, but the hypervisor support matrix is listing evacuate as 'missing' for the libvirt driver: http://docs.openstack.org/developer/nova/support-matrix.html#operation_evacuate Does anyone know why that is? The rebuild method in the compute manager just re-uses other virt driver operations so by default it's implemented by all drivers. The only one that overrides rebuild for evacuate is the ironic driver. I think it's a case where there are a couple of different things referred to with 'evacuate'. I believe this was originally added to track something that was effectively XenServer specific and the description of the feature seems to reflect that. We've since added the more generic 'evacuate' API, so it's pretty confusing. It should probably be reworked to track which drivers work with the 'evacuate' API call, and perhaps have a different entry for whatever this different XenServer thing is (or was). This is allows a host to be placed into maintenance mode, This can be done with 'nova service-disable' for libvirt, but IIRC was directly a part of the XenServer feature. automatically triggering migration of any running instances to an alternative host and preventing new instances from being launched and this isn't a part of the 'evacuate' API call at all. The API call expects that the hypervisor is gone/dead. There's no automatic moving of stuff running. -- Russell Bryant __ OpenStack Development Mailing List (not for usage questions) Unsubscribe: openstack-dev-requ...@lists.openstack.org?subject:unsubscribe http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-dev
Re: [openstack-dev] [nova] why is evacuate marked as missing for libvirt?
On 14 April 2015 at 18:44, Russell Bryant rbry...@redhat.com wrote: On 04/14/2015 12:22 PM, Matt Riedemann wrote: This came up in IRC this morning, but the hypervisor support matrix is listing evacuate as 'missing' for the libvirt driver: http://docs.openstack.org/developer/nova/support-matrix.html#operation_evacuate Does anyone know why that is? The rebuild method in the compute manager just re-uses other virt driver operations so by default it's implemented by all drivers. The only one that overrides rebuild for evacuate is the ironic driver. I think it's a case where there are a couple of different things referred to with 'evacuate'. I believe this was originally added to track something that was effectively XenServer specific and the description of the feature seems to reflect that. We've since added the more generic 'evacuate' API, so it's pretty confusing. It should probably be reworked to track which drivers work with the 'evacuate' API call, and perhaps have a different entry for whatever this different XenServer thing is (or was). This is allows a host to be placed into maintenance mode, This can be done with 'nova service-disable' for libvirt, but IIRC was directly a part of the XenServer feature. automatically triggering migration of any running instances to an alternative host and preventing new instances from being launched and this isn't a part of the 'evacuate' API call at all. The API call expects that the hypervisor is gone/dead. There's no automatic moving of stuff running. Oh right, that was part of the experimental support for XenServer pools. Basically using the pool's ability to live-migrate VMs off that host. I would be shocked if that untested feature still works, I am hoping we can finally deprecate the current XenAPI pool support soon. I would nuke that, and replace it with the regular evacuate API. (XenServer driver supports the newer evacuate API in the normal way, AFAIK). Thanks, John __ OpenStack Development Mailing List (not for usage questions) Unsubscribe: openstack-dev-requ...@lists.openstack.org?subject:unsubscribe http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-dev
