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authorQiao Fu <fuqiao@chinamobile.com>2018-11-06 08:30:02 +0000
committerGerrit Code Review <gerrit@opnfv.org>2018-11-06 08:30:02 +0000
commit1fafe69f0b0c49d45e677506a922c2e5e70ad528 (patch)
tree7ac8bba249b46872a9b1fdde788b21405fefdb7b
parentdf6a5e66e337be208705130bbc3a2e3466bd9a93 (diff)
parent053a75d02fe1842ba3e2bc0d6b019e1cdc6a6123 (diff)
Merge "Gambia Release Doc"HEADmaster
-rw-r--r--docs/development/overview/HA_Analysis-Gambia.rst35
-rw-r--r--docs/development/overview/HA_Analysis-Gambia.rst.bak667
-rw-r--r--docs/development/overview/index.rst4
-rw-r--r--docs/development/overview/index.rst.bak4
4 files changed, 687 insertions, 23 deletions
diff --git a/docs/development/overview/HA_Analysis-Gambia.rst b/docs/development/overview/HA_Analysis-Gambia.rst
index 46dc121..c5505b1 100644
--- a/docs/development/overview/HA_Analysis-Gambia.rst
+++ b/docs/development/overview/HA_Analysis-Gambia.rst
@@ -4,12 +4,9 @@
:alt: OPNFV
:align: left
-============
-High Availability Requirement Analysis in OPNFV
-============
******************
-1 Introduction
+Introduction
******************
This High Availability Requirement Analysis Document is used for eliciting High Availability
Requirements of OPNFV. The document will refine high-level High Availability goals, into
@@ -19,7 +16,7 @@ scenarios design.
A requirement engineering model KAOS is used in this document.
******************
-2 Terminologies and Symbols
+Terminologies and Symbols
******************
The following concepts in KAOS will be used in the diagrams of this document.
@@ -56,10 +53,10 @@ Figure 1 shows how these concepts are displayed in a KAOS diagram.
Fig 1. A KAOS Sample Diagram
******************
-3 High Availability Goals of OPNFV
+High Availability Goals of OPNFV
******************
-3.1 Overall Goals
+Overall Goals
>>>>>>>>>>>>>>>>>>
The Final Goal of OPNFV High Availability is to provide high available VNF services. And the
@@ -75,7 +72,7 @@ following objectives are required to meet:
-3.2 Service Level Agreements of OPNFV HA
+Service Level Agreements of OPNFV HA
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
Service Level Agreements of OPNFV HA are mainly focused on time constraints of service outage,
@@ -98,7 +95,7 @@ default benchmark value required to meet.
******************
-4 Overall Analysis
+Overall Analysis
******************
Figure 2 shows the overall decomposition of high availability goals. The high availability of
VNF Services can be refined to high availability of VNFs, MANO, and the NFVI where VNFs are
@@ -137,20 +134,20 @@ document:
The next section will illustrate detailed analysis of HA requirements on these layers.
******************
-5 Detailed Analysis
+Detailed Analysis
******************
-5.1 VNF HA
+VNF HA
>>>>>>>>>>>>>>>>>>
.. TBD
-5.2 MANO HA
+MANO HA
>>>>>>>>>>>>>>>>>>
.. TBD
-5.3 Virtual Infrastructure HA
+Virtual Infrastructure HA
>>>>>>>>>>>>>>>>>>
The Virtual Infrastructure HA in OPNFV includes container HA and VM HA.
@@ -351,7 +348,7 @@ host or container.
-5.4 VIM HA
+VIM HA
>>>>>>>>>>>>>>>>>>
@@ -385,7 +382,7 @@ figure 7.
| General | Service Crash | The processes of a service crashed unnormally. | Critical |
+------------+------------------+-------------------------------------------------+----------------+
-.. figure:: images/VIM_Analysis.png
+.. figure:: images/fig7_VIM_Analysis.png
:alt: VIM HA Analysis
:figclass: align-center
@@ -640,24 +637,24 @@ follower Components regularly through Heatbeat.
**[Req 5.4.15]** When a Master Component in the Leader state crashed, an available Master Component
should be elected as Leader.
-5.5 Hypervisor HA
+Hypervisor HA
>>>>>>>>>>>>>>>>>>
.. TBD
-5.6 Host OS HA
+Host OS HA
>>>>>>>>>>>>>>>>>>
.. TBD
-5.7 Hardware HA
+Hardware HA
>>>>>>>>>>>>>>>>>>
.. TBD
******************
-6 References
+References
******************
- A KAOS Tutorial: http://www.objectiver.com/fileadmin/download/documents/KaosTutorial.pdf
diff --git a/docs/development/overview/HA_Analysis-Gambia.rst.bak b/docs/development/overview/HA_Analysis-Gambia.rst.bak
new file mode 100644
index 0000000..40b3f35
--- /dev/null
+++ b/docs/development/overview/HA_Analysis-Gambia.rst.bak
@@ -0,0 +1,667 @@
+.. image:: opnfv-logo.png
+ :height: 40
+ :width: 200
+ :alt: OPNFV
+ :align: left
+
+
+******************
+Introduction
+******************
+This High Availability Requirement Analysis Document is used for eliciting High Availability
+Requirements of OPNFV. The document will refine high-level High Availability goals, into
+detailed HA mechanism design. And HA mechanisms are related with potential failures on
+different layers in OPNFV. Moreover, this document can be used as reference for HA Testing
+scenarios design.
+A requirement engineering model KAOS is used in this document.
+
+******************
+Terminologies and Symbols
+******************
+The following concepts in KAOS will be used in the diagrams of this document.
+
+- **Goal**: The objective to be met by the target system.
+
+- **Obstacle**: Condition whose satisfaction may prevent some goals from being achieved.
+
+- **Agent**: Active Object performing operations to achieve goals.
+
+- **Requirement**: Goal assigned to an agent of the software being studied.
+
+- **Domain Property**: Descriptive assertion about objects in the environment of the software.
+
+- **Refinement**: Relationship linking a goal to other goals that are called its subgoals.
+ Each subgoal contributes to the satisfaction of the goal it refines. There are two types of
+ refinements: AND refinement and OR refinement, which means whether the goal can be archived by
+ satisfying all of its sub goals or any one of its sub goals.
+
+- **Conflict**: Relationship linking an obstacle to a goal if the obstacle obstructs the goal
+ from being satisfied.
+
+- **Resolution**: Relationship linking a goal to an obstacle if the goal can resolve the
+ obstacle.
+
+- **Responsibility**: Relationship between an agent and a requirement. Holds when an agent is
+ assigned the responsibility of achieving the linked requirement.
+
+Figure 1 shows how these concepts are displayed in a KAOS diagram.
+
+.. figure:: images/fig1_KAOS_Sample.png
+ :alt: KAOS Sample
+ :figclass: align-center
+
+ Fig 1. A KAOS Sample Diagram
+
+******************
+High Availability Goals of OPNFV
+******************
+
+Overall Goals
+>>>>>>>>>>>>>>>>>>
+
+The Final Goal of OPNFV High Availability is to provide high available VNF services. And the
+following objectives are required to meet:
+
+- There should be no single point of failure in the NFV framework.
+
+- All resiliency mechanisms shall be designed for a multi-vendor environment, where for example
+ the NFVI, NFV-MANO, and VNFs may be supplied by different vendors.
+
+- Resiliency related information shall always be explicitly specified and communicated using
+ the reference interfaces (including policies/templates) of the NFV framework.
+
+
+
+Service Level Agreements of OPNFV HA
+>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
+
+Service Level Agreements of OPNFV HA are mainly focused on time constraints of service outage,
+failure detection, failure recovery. The following table outlines the SLA metrics of different
+service availability levels described in ETSI GS NFV-REL 001 V1.1.1 (2015-01). Table 1 shows
+time constraints of different Service Availability Levels. In this document, SAL1 is the
+default benchmark value required to meet.
+
+*Table 1. Time Constraints for Different Service Availability Levels*
+
++--------------------------------+----------------------------+------------------------+
+| Service Availability Level | Failure Detection Time | Failure Recovery Time |
++================================+============================+========================+
+| SAL1 | <1s | 5-6s |
++--------------------------------+----------------------------+------------------------+
+| SAL2 | <5s | 10-15s |
++--------------------------------+----------------------------+------------------------+
+| SAL3 | <10s | 20-25s |
++--------------------------------+----------------------------+------------------------+
+
+
+******************
+Overall Analysis
+******************
+Figure 2 shows the overall decomposition of high availability goals. The high availability of
+VNF Services can be refined to high availability of VNFs, MANO, and the NFVI where VNFs are
+deployed; the high availability of NFVI Service can be refined to high availability of Virtual
+Compute Instances, Virtual Storage and Virtual Network Services; the high availability of
+virtual instance is either the high availability of containers or the high availability of VMs,
+and these high availability goals can be further decomposed by how the NFV environment is
+deployed.
+
+.. figure:: images/fig2_Total_Framework.png
+ :alt: Overall HA Analysis of OPNFV
+ :figclass: align-center
+
+ Fig 2. Overall HA Analysis of OPNFV
+
+Thus the high availability requirement of VNF services can be classified into high availability
+requirements on different layers in OPNFV. The following layers are mainly discussed in this
+document:
+
+- VNF HA
+
+- MANO HA
+
+- Virtual Infrastructure HA (container HA or VM HA)
+
+- VIM HA
+
+- SDN HA
+
+- Hypervisor HA
+
+- Host OS HA
+
+- Hardware HA
+
+The next section will illustrate detailed analysis of HA requirements on these layers.
+
+******************
+Detailed Analysis
+******************
+
+VNF HA
+>>>>>>>>>>>>>>>>>>
+
+.. TBD
+
+MANO HA
+>>>>>>>>>>>>>>>>>>
+
+.. TBD
+
+Virtual Infrastructure HA
+>>>>>>>>>>>>>>>>>>
+
+The Virtual Infrastructure HA in OPNFV includes container HA and VM HA.
+
+VM HA
+::::::::::::::::::::::::::::::::::::::
+
+This part describes a set of new optional capabilities where the OpenStack Cloud messages into the Guest
+VMs in order to provide improved Availability of the Host VMs.
+
+Table 2 shows the potential faults of VMs and corresponding initial solution capabilities or methods.
+
+*Table 2. Potential Faults of VMs and the initial solution capabilities*
+
++---------------------------+------------------------------------+--------------------------------------------+
+| Fault | Description | solution capabilities |
++===========================+====================================+============================================+
+| VM faults | General internal VM faults | VM Heartbeating and Health Checking |
++---------------------------+------------------------------------+--------------------------------------------+
+| VM Server Group faults | such as split brain | VM Peer State Notification and Messaging |
++---------------------------+------------------------------------+--------------------------------------------+
+
+
+.. figure:: images/fig3_VM_HA_Analysis.png
+ :alt: VM HA
+ :figclass: align-center
+
+ Fig 3. VM HA Analysis
+
+NOTE: A Server Group here is the OpenStack Nova Server Group concept where VMs
+are grouped together for purposes of scheduling. E.g. A specific Server Group
+instance can specify whether the VMs within the group should be scheduled to
+run on the same compute host or different compute hosts. A 'peer' VM in the
+context of this section refers to a VM within the same Nova Server Group.
+
+The initial set of new capabilities include: enabling the
+detection of and recovery from internal VM faults and providing
+a simple out-of-band messaging service to prevent scenarios such
+as split brain.
+
+More detailed description is located in R5_HA_API/OPNFV_HA_Guest_APIs-Overview_HLD.rst in this project.
+
+The Host-to-Guest messaging APIs used by the services discussed
+in this Virtual Infrastructure HA part use a JSON-formatted application messaging layer
+on top of a virtio serial device between QEMU on the OpenStack Host
+and the Guest VM. Use of the virtio serial device provides a
+simple, direct communication channel between host and guest which is
+independent of the Guest's L2/L3 networking.
+
+The upper layer JSON messaging format is actually structured as a
+hierarchical JSON format containing a Base JSON Message Layer and an
+Application JSON Message Layer:
+
+- the Base Layer provides the ability to multiplex different groups of message types on top of a single virtio serial device
+e.g.
+
+ + heartbeating and healthchecks,
+ + server group messaging,
+
+and
+
+- the Application Layer provides the specific message types and fields of a particular group of message types.
+
+
+A) VM Heartbeating and Health Checking
+
+
+.. figure:: images/fig4_Heartbeating_and_Healthchecks.png
+ :alt: Heartbeating and Healthchecks
+ :figclass: align-center
+
+ Fig 4. Heartbeating and Healthchecks
+
+VM Heartbeating and Health Checking provides a heartbeat service to enhance
+the monitoring of the health of guest application(s) within a VM running
+under the OpenStack Cloud. Loss of heartbeat or a failed health check status
+will result in a fault event being reported to OPNFV's DOCTOR infrastructure
+for alarm identification, impact analysis and reporting. This would then enable
+VNF Managers (VNFMs) listening to OPNFV's DOCTOR External Alarm Reporting through
+Telemetry's AODH, to initiate any required fault recovery actions.
+
+Guest heartbeat works on a challenge response model. The OpenStack Guest Heartbeat
+Service on the compute node will challenge the registered Guest VM daemon with a
+message each interval. The registered Guest VM daemon must respond prior to the
+next interval with a message indicating good health. If the OpenStack Host does
+not receive a valid response, or if the response specifies that the VM is in ill
+health, then a fault event for the Guest VM is reported to the OpenStack Guest
+Heartbeat Service on the controller node which will report the event to OPNFV's
+DOCTOR (i.e. thru the Doctor SouthBound (SB) APIs).
+
+In summary, the Guest Heartbeating Messaging Specification is quite simple,
+including the following PDUs: Init, Init-Ack, Challenge-Request,
+Challenge-Response, Exit. The Challenge-Response returning a healthy /
+not-healthy boolean.
+
+The registered Guest VM daemon's response to the challenge can be as simple
+as just immediately responding with OK. This alone allows for detection of
+a failed or hung QEMU/KVM instance, or a failure of the OS within the VM to
+schedule the registered Guest VM's daemon or failure to route basic IO within
+the Guest VM.
+
+However the registered Guest VM daemon's response to the challenge can be more
+complex, running anything from a quick simple sanity check of the health of
+applications running in the Guest VM, to a more thorough audit of the
+application state and data. In either case returning the status of the
+health check enables the OpenStack host to detect and report the event in order
+to initiate recovery from application level errors or failures within the Guest VM.
+
+
+B) VM Peer State Notification and Messaging
+
+
+.. figure:: images/fig5_VM_Peer_State_Notification_and_Messaging.png
+ :alt: VM Peer State Notification and Messaging
+ :figclass: align-center
+
+ Fig 5. VM Peer State Notification and Messaging
+
+Server Group State Notification and Messaging is a service to provide
+simple low-bandwidth datagram messaging and notifications for servers that
+are part of the same server group. This messaging channel is available
+regardless of whether IP networking is functional within the server, and
+it requires no knowledge within the server about the other members of the group.
+
+This Server Group Messaging service provides three types of messaging:
+
+- Broadcast: this allows a server to send a datagram (size of up to 3050 bytes)
+ to all other servers within the server group.
+- Notification: this provides servers with information about changes to the
+ (Nova) state of other servers within the server group.
+- Status: this allows a server to query the current (Nova) state of all servers within
+ the server group (including itself).
+
+A Server Group Messaging entity on both the controller node and the compute nodes manage
+the routing of of VM-to-VM messages through the platform, leveraging Nova to determine
+Server Group membership and compute node locations of VMs. The Server Group Messaging
+entity on the controller also listens to Nova VM state change notifications and querys
+VM state data from Nova, in order to provide the VM query and notification functionality
+of this service.
+
+This service is not intended for high bandwidth or low-latency operations. It is best-effort,
+not reliable. Applications should do end-to-end acks and retries if they care about reliability.
+
+This service provides building block type capabilities for the Guest VMs that
+contribute to higher availability of the VMs in the Guest VM Server Group. Notifications
+of VM Status changes potentially provide a faster and more accurate notification
+of failed peer VMs than traditional peer VM monitoring over Tenant Networks. While
+the Broadcast Messaging mechanism provides an out-of-band messaging mechanism to
+monitor and control a peer VM under fault conditions; e.g. providing the ability to
+avoid potential split brain scenarios between 1:1 VMs when faults in Tenant
+Networking occur.
+
+Container HA
+::::::::::::::::::::::::::::
+
+The container HA in OPNFV is mainly focus on Kubernetes(K8s) platform. And using the Pod as
+the smallest unit of management, creation, and planning, the K8s' container HA actually means
+the High Availability of running Pods.
+
+Table 3 shows the potential faults of running pods in K8s. when it happens, the ReplicationController
+or ReplicaSet can prevent the services provided by the pod from being unavailable, as is shown in
+figure 6.
+
+*Table 3. Potential Faults in VIM level*
+
++------------+--------------+----------------------------------------------------+----------------+
+| Service | Fault | Description | Severity |
++============+==============+====================================================+================+
+| | | All Containers in the Pod have terminated, and | |
+| Running by | Pod failure | at least one Container has terminated in failure. | Critical |
+| pods | | That is, the Container either exited with non-zero | |
+| | | status or was terminated by the system. | |
++------------+--------------+----------------------------------------------------+----------------+
+
+.. figure:: images/fig6_Container_HA_analysis_in_K8s.png
+ :alt: VIM HA Analysis
+ :figclass: align-center
+
+ Fig 6. Container HA analysis in K8s
+
+
+The Replication Controller or ReplicaSet (ReplicaSet is the next-generation Replication Controller)
+is a kind of K8s Master Components, which ensures that a specified number of pod replicas are running
+at any one time.
+
+The following requirements are elicited for Pod HA:
+
+**[Req 5.3.1]** A pod or a homogeneous set of pods is always up and available until terminated properly.
+
+**[Req 5.3.2]** The ReplicationController or ReplicaSet should terminate the extra pods If there are
+more pods than specified number.
+
+**[Req 5.3.3]** The ReplicationController or ReplicaSet should start more pods If there are fewer pods
+than specified number.
+
+**[Req 5.3.4]** The new Pod should be scheduled to other Nodes, if detecting the failure state of the
+host or container.
+
+
+
+VIM HA
+>>>>>>>>>>>>>>>>>>
+
+
+OpenStack High Availability
+::::::::::::::::::::::::::::
+
+The VIM in the NFV reference architecture contains different components of Openstack, SDN
+controllers and other virtual resource controllers. VIM components can be classified into three
+types:
+
+- **Entry Point Components**: Components that give VIM service interfaces to users, like nova-
+ api, neutron-server.
+
+- **Middlewares**: Components that provide load balancer services, messaging queues, cluster
+ management services, etc.
+
+- **Subcomponents**: Components that implement VIM functions, which are called by Entry Point
+ Components but not by users directly.
+
+Table 4 shows the potential faults that may happen on VIM layer. Currently the main focus of
+VIM HA is the service crash of VIM components, which may occur on all types of VIM components.
+To prevent VIM services from being unavailable, Active/Active Redundancy, Active/Passive
+Redundancy and Message Queue are used for different types of VIM components, as is shown in
+figure 7.
+
+*Table 4. Potential Faults in VIM level*
+
++------------+------------------+-------------------------------------------------+----------------+
+| Service | Fault | Description | Severity |
++============+==================+=================================================+================+
+| General | Service Crash | The processes of a service crashed unnormally. | Critical |
++------------+------------------+-------------------------------------------------+----------------+
+
+.. figure:: images/VIM_Analysis.png
+ :alt: VIM HA Analysis
+ :figclass: align-center
+
+ Fig 7. VIM HA Analysis
+
+
+A) Active/Active Redundancy
+
+Active/Active Redundancy manages both the main and redundant systems concurrently. If there is
+a failure happens on a component, the backups are already online and users are unlikely to
+notice that the failed VIM component is under fixing. A typical Active/Active Redundancy will
+have redundant instances, and these instances are load balanced via a virtual IP address and a
+load balancer such as HAProxy.
+
+When one of the redundant VIM component fails, the load balancer should be aware of the
+instance failure, and then isolate the failed instance from being called until it is recovered.
+The requirement decomposition of Active/Active Redundancy is shown in Figure 8.
+
+.. figure:: images/fig8_Active_Active_Redundancy.png
+ :alt: Active/Active Redundancy Requirement Decomposition
+ :figclass: align-center
+
+ Fig 8. Active/Active Redundancy Requirement Decomposition
+
+The following requirements are elicited for VIM Active/Active Redundancy:
+
+**[Req 5.4.1]** Redundant VIM components should be load balanced by a load balancer.
+
+**[Req 5.4.2]** The load balancer should check the health status of VIM component instances.
+
+**[Req 5.4.3]** The load balancer should isolate the failed VIM component instance until it is
+recovered.
+
+**[Req 5.4.4]** The alarm information of VIM component failure should be reported.
+
+**[Req 5.4.5]** Failed VIM component instances should be recovered by a cluster manager.
+
+Table 5 shows the current VIM components using Active/Active Redundancy and the corresponding
+HA test cases to verify them.
+
+*Table 5. VIM Components using Active/Active Redundancy*
+
++-------------------+-------------------------------------------------------+----------------------+
+| Component | Description | Related HA Test Case |
++===================+=======================================================+======================+
+| nova-api | endpoint component of Openstack Compute Service Nova | yardstick_tc019 |
++-------------------+-------------------------------------------------------+----------------------+
+| nova-novncproxy | server daemon that serves the Nova noVNC Websocket | |
+| | Proxy service, which provides a websocket proxy that | |
+| | is compatible with OpenStack Nova noVNC consoles. | |
++-------------------+-------------------------------------------------------+----------------------+
+| neeutron-server | endpoint component of Openstack Networking Service | yardstick_tc045 |
+| | Neutron | |
++-------------------+-------------------------------------------------------+----------------------+
+| keystone | component of Openstack Identity Service Service | yardstick_tc046 |
+| | Keystone | |
++-------------------+-------------------------------------------------------+----------------------+
+| glance-api | endpoint component of Openstack Image Service Glance | yardstick_tc047 |
++-------------------+-------------------------------------------------------+----------------------+
+| glance-registry | server daemon that serves image metadata through a | |
+| | REST-like API. | |
++-------------------+-------------------------------------------------------+----------------------+
+| cinder-api | endpoint component of Openstack Block Storage Service | yardstick_tc048 |
+| | Service Cinder | |
++-------------------+-------------------------------------------------------+----------------------+
+| swift-proxy | endpoint component of Openstack Object Storage | yardstick_tc049 |
+| | Swift | |
++-------------------+-------------------------------------------------------+----------------------+
+| horizon | component of Openstack Dashboard Service Horizon | |
++-------------------+-------------------------------------------------------+----------------------+
+| heat-api | endpoint component of Openstack Stack Service Heat | yardstick_tc091 |
++-------------------+-------------------------------------------------------+----------------------+
+| mysqld | database service of VIM components | yardstick_tc090 |
++-------------------+-------------------------------------------------------+----------------------+
+
+B)Active/Passive Redundancy
+
+
+Active/Passive Redundancy maintains a redundant instance that can be brought online when the
+active service fails. A typical Active/Passive Redundancy maintains replacement resources that
+can be brought online when required. Requests are handled using a virtual IP address (VIP) that
+facilitates returning to service with minimal reconfiguration. A cluster manager (such as
+Pacemaker or Corosync) monitors these components, bringing the backup online as necessary.
+
+When the main instance of a VIM component is failed, the cluster manager should be aware of the
+failure and switch the backup instance online. And the failed instance should also be recovered
+to another backup instance. The requirement decomposition of Active/Passive Redundancy is shown
+in Figure 9.
+
+.. figure:: images/fig9_Active_Passive_Redundancy.png
+ :alt: Active/Passive Redundancy Requirement Decomposition
+ :figclass: align-center
+
+ Fig 9. Active/Passive Redundancy Requirement Decomposition
+
+The following requirements are elicited for VIM Active/Passive Redundancy:
+
+**[Req 5.4.6]** The cluster manager should replace the failed main VIM component instance with
+a backup instance.
+
+**[Req 5.4.7]** The cluster manager should check the health status of VIM component instances.
+
+**[Req 5.4.8]** Failed VIM component instances should be recovered by the cluster manager.
+
+**[Req 5.4.9]** The alarm information of VIM component failure should be reported.
+
+
+Table 6 shows the current VIM components using Active/Passive Redundancy and the corresponding
+HA test cases to verify them.
+
+*Table 6. VIM Components using Active/Passive Redundancy*
+
++-------------------+-------------------------------------------------------+----------------------+
+| Component | Description | Related HA Test Case |
++===================+=======================================================+======================+
+| haproxy | load balancer component of VIM components | yardstick_tc053 |
++-------------------+-------------------------------------------------------+----------------------+
+| rabbitmq-server | messaging queue service of VIM components | yardstick_tc056 |
++-------------------+-------------------------------------------------------+----------------------+
+| corosync | cluster management component of VIM components | yardstick_tc057 |
++-------------------+-------------------------------------------------------+----------------------+
+
+C) Message Queue
+
+Message Queue provides an asynchronous communication protocol. In Openstack, some projects (
+like Nova, Cinder) use Message Queue to call their sub components. Although Message Queue
+itself is not an HA mechanism, how it works ensures the high availaibility when redundant
+components subscribe to the Messsage Queue. When a VIM sub component fails, since there are
+other redundant components are subscribing to the Message Queue, requests still can be processed.
+And fault isolation can also be archived since failed components won't fetch requests actively.
+Also, the recovery of failed components is required. Figure 10 shows the requirement
+decomposition of Message Queue.
+
+.. figure:: images/fig10_Message_Queue.png
+ :alt: Message Queue Requirement Decomposition
+ :figclass: align-center
+
+ Fig 10. Message Queue Redundancy Requirement Decomposition
+
+The following requirements are elicited for Message Queue:
+
+**[Req 5.4.10]** Redundant component instances should subscribe to the Message Queue, which is
+implemented by the installer.
+
+**[Req 5.4.11]** Failed VIM component instances should be recovered by the cluster manager.
+
+**[Req 5.4.12]** The alarm information of VIM component failure should be reported.
+
+Table 7 shows the current VIM components using Message Queue and the corresponding HA test cases
+to verify them.
+
+*Table 7. VIM Components using Messaging Queue*
+
++-------------------+-------------------------------------------------------+----------------------+
+| Component | Description | Related HA Test Case |
++===================+=======================================================+======================+
+| nova-scheduler | Openstack compute component determines how to | yardstick_tc088 |
+| | dispatch compute requests | |
++-------------------+-------------------------------------------------------+----------------------+
+| nova-cert | Openstack compute component that serves the Nova Cert | |
+| | service for X509 certificates. Used to generate | |
+| | certificates for euca-bundle-image. | |
++-------------------+-------------------------------------------------------+----------------------+
+| nova-conductor | server daemon that serves the Nova Conductor service, | yardstick_tc089 |
+| | which provides coordination and database query | |
+| | support for Nova. | |
++-------------------+-------------------------------------------------------+----------------------+
+| nova-compute | Handles all processes relating to instances (guest | |
+| | vms). nova-compute is responsible for building a disk | |
+| | image, launching it via the underlying virtualization | |
+| | driver, responding to calls to check its state, | |
+| | attaching persistent storage, and terminating it. | |
++-------------------+-------------------------------------------------------+----------------------+
+| nova-consoleauth | Openstack compute component for Authentication of | |
+| | nova consoles. | |
++-------------------+-------------------------------------------------------+----------------------+
+| cinder-scheduler | Openstack volume storage component decides on | |
+| | placement for newly created volumes and forwards the | |
+| | request to cinder-volume. | |
++-------------------+-------------------------------------------------------+----------------------+
+| cinder-volume | Openstack volume storage component receives volume | |
+| | management requests from cinder-api and | |
+| | cinder-scheduler, and routes them to storage backends | |
+| | using vendor-supplied drivers. | |
++-------------------+-------------------------------------------------------+----------------------+
+| heat-engine | Openstack Heat project server with an internal RPC | |
+| | api called by the heat-api server. | |
++-------------------+-------------------------------------------------------+----------------------+
+
+
+VIM HA in K8s
+::::::::::::::::::::::::::::
+
+The VIM HA in K8s can be generally analyzed from the following two concepts:
+
+- **Master Components HA**: the HA of k8s components in Master. (for example, Kube-apiserver,
+ Kube-scheduler, Kube-controller-manager)
+
+- **Data Storage HA**: the HA of etcd cluster. Actually etcd is a master component used as
+ Kubernetes' backing store for all cluster data. Considering that etcd is the only stateful service
+ in k8s and that its HA policy can be deployed independent on K8s, it is necessary to discuss the
+ HA of etcd separately.
+
+Table 8 shows the potential faults that may happen in K8s.
+
+*Table 8. Potential Faults in K8s*
+
++--------------------+------------------+----------------------------------------+----------------+
+| Service | Fault | Description | Severity |
++====================+==================+========================================+================+
+| Provided by Master | Master | A Master component crashed and can't | Critical |
+| Components | Component crash | provide normal service. | |
++--------------------+------------------+----------------------------------------+----------------+
+| Data storage | Etcd Crash | The Etcd cluster crashed unnormally. | Critical |
++--------------------+------------------+----------------------------------------+----------------+
+
+
+.. figure:: images/fig11_VIM_HA_analysis_in_K8s.png
+ :alt: Message Queue Requirement Decomposition
+ :figclass: align-center
+
+ Fig 11. VIM HA analysis in K8s
+
+Master components can be run on any machine in the cluster. However, for simplicity, all master
+components are typically started on the same machine, and do not run user containers on this machine.
+In this case, the K8s is based on a single Master, and only has container HA on application layer
+realized by ReplicationController or ReplicaSet Master Component as mentioned in the container HA
+part above.
+
+The HA of Mater and its components in K8s must depend on the multi-master setup.
+
+The Data Storage HA can use an existing Etcd HA cluster to realize, or can be realized as a master
+component through multiple master implementation.
+
+.. figure:: images/fig12_VIM_HA_analysis_in_K8s_2.png
+ :alt: Message Queue Requirement Decomposition
+ :figclass: align-center
+
+ Fig 12. VIM HA analysis in K8s(2)
+
+In Multi-Master K8s, the Master Components HA is mainly based on the Leader Election function of Etcd
+cluster. And load balancer is used to realize the HA of Kube-apiserver Master component.
+
+The following requirements are elicited for Master components HA:
+
+**[Req 5.4.13]** The Load Balancer should always forward the request to an available Kube-apiserver
+instance.
+
+**[Req 5.4.14]** The Master Component in the Leader state should confirm its Leader state to all
+follower Components regularly through Heatbeat.
+
+**[Req 5.4.15]** When a Master Component in the Leader state crashed, an available Master Component
+should be elected as Leader.
+
+Hypervisor HA
+>>>>>>>>>>>>>>>>>>
+
+.. TBD
+
+Host OS HA
+>>>>>>>>>>>>>>>>>>
+
+.. TBD
+
+Hardware HA
+>>>>>>>>>>>>>>>>>>
+
+.. TBD
+
+
+******************
+References
+******************
+
+- A KAOS Tutorial: http://www.objectiver.com/fileadmin/download/documents/KaosTutorial.pdf
+
+- ETSI GS NFV-REL 001 V1.1.1(2015-01):
+ http://www.etsi.org/deliver/etsi_gs/NFV-REL/001_099/001/01.01.01_60/gs_NFV-REL001v010101p.pdf
+
+- Openstack High Availability Guide: https://docs.openstack.org/ha-guide/
+
+- Highly Available (Mirrored) Queues: https://www.rabbitmq.com/ha.html
diff --git a/docs/development/overview/index.rst b/docs/development/overview/index.rst
index 3e69259..e6f5d93 100644
--- a/docs/development/overview/index.rst
+++ b/docs/development/overview/index.rst
@@ -5,9 +5,9 @@
.. (c) <optionally add copywriters name>
-*********************************************************************************
+=======================================================================
High Availability Requirement Analysis in OPNFV
-*********************************************************************************
+=======================================================================
.. toctree::
:maxdepth: 4
diff --git a/docs/development/overview/index.rst.bak b/docs/development/overview/index.rst.bak
index 1114613..3e69259 100644
--- a/docs/development/overview/index.rst.bak
+++ b/docs/development/overview/index.rst.bak
@@ -6,10 +6,10 @@
*********************************************************************************
-Reach-thru Guest Monitoring and Services for High Availability
+High Availability Requirement Analysis in OPNFV
*********************************************************************************
.. toctree::
:maxdepth: 4
- OPNFV_HA_Guest_APIs-Overview_HLD.rst
+ HA_Analysis-Gambia.rst