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authorfuqiao <fuqiao@chinamobile.com>2016-09-21 11:18:34 +0800
committerfuqiao <fuqiao@chinamobile.com>2016-09-22 17:45:31 +0800
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tree673c2b3d091d02970c43a6814ee44687b0ebfa3e /docs/scenarios/GAP_Analysis_Colorado.rst.bak
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Update the docs folder
Update the docs folder to include the two release docs JIRA: HA-24 Change-Id: I2d50fb84b9e54ae6b6e05d0f9466e920a8dae1d4 Signed-off-by: fuqiao@chinamobile.com
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+Introduction:
+^^^^^^^^^^^^^
+
+During the Colorado release the OPNFV availability team has reviewed a number of gaps
+in support for high availability in various areas of OPNFV. The focus and goal was
+to find gaps and work with the various open source communities( OpenStack as an
+example ) to develop solutions and blueprints. This would enhance the overall
+system availability and reliability of OPNFV going forward. We also worked with
+the OPNFV Doctor team to ensure our activities were coordinated. In the next
+releases of OPNFV the availability team will update the status of open gaps and
+continue to look for additional gaps.
+
+Summary of findings:
+^^^^^^^^^^^^^^^^^^^^
+
+1. Publish health status of compute node - this gap is now closed through and
+OpenStack blueprint in Mitaka
+
+2. Health status of compute node - some good work underway in OpenStack and with
+the Doctor team, we will continue to monitor this work.
+
+3. Store consoleauth tokens to the database - this gap can be address through
+changing OpenStack configurations
+
+4. Active/Active HA of cinder-volume - active work underway in Newton, we will
+monitor closely
+
+5. Cinder volume multi-attachment - this work has been completed in OpenStack -
+this gap is now closed
+
+6. Add HA tests into Fuel - the Availability team has been working with the
+Yardstick team to create additional test case for the Colorado release. Some of
+these test cases would be good additions to installers like Fuel.
+
+Detailed explanation of the gaps and findings:
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+GAP 1: Publish the health status of compute node
+================================================
+
+* Type: 'reliability'
+* Description:
+
+ Current compute node status is only kept within nova. However, NFVO and VNFM
+ may also need these information. For example, NFVO may trigger scale up/down
+ based on the status. VNFM may trigger evacuation. In the meantime, in the
+ high availability scenarios, VNFM may need the host status info from the VIM
+ so that it can figure out what the failure exactly located. Therefore, these
+ info need to be published outside to the NFVO and VNFM.
+
+ + Desired state
+
+ - Be able to have the health status of compute nodes published.
+
+ + Current behaviour
+
+ - Nova queries the ServiceGroup API to get the node liveness information.
+
+ + Gap
+
+- Currently Service Group is keeping the health status of compute nodes internal
+- within nova, could have had those status published to NFV MANO plane.
+
+Findings:
+
+BP from the OPNFV Doctor team has covered this GAP. Add notification for service
+status change.
+
+Status: Merged (Mitaka release)
+
+ + Owner: Balazs
+
+ + BP: https://blueprints.launchpad.net/nova/+spec/service-status-notification
+
+ + Spec: https://review.openstack.org/182350
+
+ + Code: https://review.openstack.org/#/c/245678/
+
+ + Merged Jan 2016 - Mitaka
+
+GAP 2: Health status of compute node
+====================================
+
+* Type: 'reliability'
+* Description:
+
+ + Desired state:
+
+ - Provide the health status of compute nodes.
+
+ + Current Behaviour
+
+ - Currently , while performing some actions like evacuation, Nova is
+ checking for the compute service. If the service is down,it is assumed
+ the host is down. This is not exactly true, since there is a possibility
+ to only have compute service down, while all VMs that are running on the
+ host, are actually up. There is no way to distinguish between two really
+ different things: host status and nova-compute status, which is deployed
+ on the host.
+ - Also, provided host information by API and commands, are service centric,
+ i.e."nova host-list" is just another wrapper for "nova service-list" with
+ different format (in fact "service-list" is a super set to "host-list").
+
+
+ + Gap
+
+ - Not all the health information of compute nodes can be provided. Seems like
+ nova is treating *host* term equally to *compute-host*, which might be misleading.
+ Such situations can be error prone for the case where there is a need to perform
+ host evacuation.
+
+
+Related BP:
+
+Pacemaker and Corosync can provide info about the host. Therefore, there is
+requirement to have nova support the pacemaker service group driver. There could
+be another option by adding tooz servicegroup driver to nova, and then have to
+support corosync driver.
+
+ + https://blueprints.launchpad.net/nova/+spec/tooz-for-service-groups
+
+Doctor team is not working on this blueprint
+
+NOTE: This bp is active. A suggestion is to adopt this bp and add a corosync
+driver to tooz. Could be a solution.
+
+We should keep following this bp, when it finished, see if we could add a
+corosync driver for tooz to close this gap.
+
+Here are the currently supported driver in tooz.
+https://github.com/openstack/tooz/blob/master/doc/source/drivers.rst Meanwhile,
+we should also look into the doctor project and see if this could be solved.
+
+This work is still underway, but, doesn't directly map to the gap that it is
+identified above. Doctor team looking to get faster updates on node status and
+failure status - these are other blueprints. These are good problems to solve.
+
+GAP 3: Store consoleauth tokens to the database
+===============================================
+
+* Type: 'performance'
+* Description:
+
++ Desired state
+
+ - Change the consoleauth service to store the tokens in the databaseand, optionally,
+ cache them in memory as it does now for fast access.
+
++ Current State
+
+ - Currently the consoleauth service is storing the tokens and theconnection data
+ only in memory. This behavior makes impossible to have multipleinstances of this
+ service in a cluster as there is no way for one of theisntances to know the tokens
+ issued by the other.
+
+ - The consoleauth service can use a memcached server to store those tokens,but again,
+ if we want to share them among different instances of it we would berelying in one
+ memcached server which makes this solution unsuitable for a highly available
+ architecture where we should be able to replicate all ofthe services in our cluster.
+
++ Gap
+
+ - The consoleauth service is storing the tokens and the connection data only in memory.
+ This behavior makes impossible to have multiple instances of this service in a cluster
+ as there is no way for one of the instances to know the tokens issued by the other.
+
+* Related BP
+
+ + https://blueprints.launchpad.net/nova/+spec/consoleauth-tokens-in-db
+
+ The advise in the blueprint is to use memcached as a backend. Looking to the
+ documentation memcached is not able to replicate data, so this is not a
+ complete solution. But maybe redis (http://redis.io/) is a suitable backend
+ to store the tokens that survive node failures. This blueprint is not
+ directly needed for this gap.
+
+Findings:
+
+This bp has been rejected since the community feedback is that A/A can be
+supported by memcacheD. The usecase for this bp is not quite clear, since when
+the consoleauth service is done and the token is lost, the other service can
+retrieve the token again after it recovers. Can be accomplished through a
+different configuration set up for OpenStack. Therefore not a gap.
+Recommendation of the team is to verify the redis approach.
+
+
+GAP 4: Active/Active HA of cinder-volume
+========================================
+
+* Type: 'reliability/scalability'
+
+* Description:
+
+ + Desired State:
+
+ - Cinder-volume can run in an active/active configuration.
+
+ + Current State:
+
+ - Only one cinder-volume instance can be active. Failover to be handledby
+ external mechanism such as pacemaker/corosync.
+
+ + Gap
+
+ - Cinder-volume doesn't supprt active/active configuration.
+
+* Related BP
+
+ + https://blueprints.launchpad.net/cinder/+spec/cinder-volume-active-active-support
+
+* Findings:
+
+ + This blueprint underway for Newton - as of July 6, 2016 great progress has
+ been made, we will continue to monitor the progress.
+
+GAP 5: Cinder volume multi-attachment
+=====================================
+
+* Type: 'reliability'
+* Description:
+
+ + Desired State
+
+ - Cinder volumes can be attached to multiple VMs at the same time. So that
+ active/standby stateful VNFs can share the same Cinder volume.
+
+ + Current State
+
+ - Cinder volumes can only be attached to one VM at a time.
+
+ + Gap
+
+ - Nova and cinder do not allow for multiple simultaneous attachments.
+
+* Related BP
+
+ + https://blueprints.launchpad.net/openstack/?searchtext=multi-attach-volume
+
+* Findings
+
+ + Multi-attach volume is still WIP in OpenStack. There is coordination work required with Nova.
+ + At risk for Newton
+ + Recommend adding a Yardstick test case.
+
+General comment for the next release. Remote volume replication is another
+important project for storage HA.
+The HA team will monitor this multi-blueprint activity that will span multiple
+OpenStack releases. The blueprints aren't approved yet and there dependencies
+on generic-volume-group.
+
+
+
+GAP 6: HA tests improvements in fuel
+====================================
+
+* Type: 'robustness'
+* Description:
+
+ + Desired State
+ - Increased test coverage for HA during install
+ + Current State
+ - A few test cases are available
+
+ * Related BP
+
+ - https://blueprints.launchpad.net/fuel/+spec/ha-test-improvements
+ - Tie in with the test plans we have discussed previously.
+ - Look at Yardstick tests that could be proposed back to Openstack.
+ - Discussions planned with Yardstick team to engage with Openstack community to enhance Fuel or Tempest as appropriate.
+
+
+Next Steps:
+^^^^^^^^^^^
+
+The six gaps above demonstrate that on going progress is being made in various
+OPNFV and OpenStack communities. The OPNFV-HA team will work to suggest
+blueprints for the next OpenStack Summit to help continue the progress of high
+availability in the community.