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diff --git a/docs/userguide/Deployment_Guideline.rst b/docs/userguide/Deployment_Guideline.rst new file mode 100644 index 0000000..d6a8cf3 --- /dev/null +++ b/docs/userguide/Deployment_Guideline.rst @@ -0,0 +1,453 @@ +This document will provide an overall framework for the high availability +deployment of NFV system. It will also continiously update to include HA +deployment guidelines and suggestions for the releases of OPNFV. + +********************************************************************* +Overview of High Available Deployment of OPNFV +********************************************************************* + +In this section, we would like to discuss the overall HA deployment of NFV system. +Different modules, such as hardware,VIM,VMs and etc, will be included, and HA +deployment of each single module will be discussed. However, not all of these HA +schemes should be deployed in on system at the same time. For the HA deployment of +a single system, we should consider the tradeoff between high availability and the +cost and resource to leverage. + + +Architecture of HA deployment +================================================================== + +This section intends to introduce the different modules we should consider +when talking about HA deployment. These moduels include the Hardware +(compute, network, storage hardware), the VIM, the hypervisor, VMs and VNFs. +HA schemes for these different moduels should all be considered when deploying +an NFV system. And the schemes should be coordinated so that the system can make +sure to react in its best way when facing failure. + +The following picture shows the the architecture of HA deployment based on the +framework from ETSI NFV ISG. + +.. figure:: Overview.jpg + :alt: Architecture for HA Deployment + :figclass: align-center + + Fig 1. Architecture of HA Deployment based on the Framework of ETSI NFV ISG + +HA deployment topology +================================================================== + +This section will introduce the HA deployment topology for an NFV system. +The topology explained in this section is to support the software +cluster of OPNFV platform, which we will discuss in detail in section1.3. + +The typical topology of deployment OPNFV platform should include at +least the controller nodes, and the compute nodes. Depend on the request of +the users, standalone network nodes or storage nodes can be added into this +topology. The simplest HA deployment of OPNFV only include the control nodes. Further +HA schemes can be provided to the compute nodes, the network nodes and the storage +nodes, according to the requirement of services deployed on the NFV system. +Figure 2 shows the deployment topology, in which the controller nodes are all in +a cluster, and the compute nodes can be in another cluster. + +The control node cluster here is to provide HA for the controller services, so +that the services on the control node can successfully failover when failure +happens and the service can continue. The cluster service should also provide +automatic recovery for the control nodes. For OPNFV, the control node cluster +should include at least 3 nodes, and should be an odd number if the cluster +management system use quorum. This may change if we use different cluster +management schemes though. + +The compute node clusters is responsible for providing HA for the services running +on the compute nodes. These services may include agents for openstack, host os, +hypervisors. Such cluster is responsible for the recovery and repair +of the services. However, compute node cluster will certainly bring complexity to +the whole system, and would increase the cost. There could be multiple solutions +for the compute cluster, e.g., senlin from openstack. + +There could be other HA solutions for the compute nodes except for cluster. Combination +of congress and doctor can be one of them, in which doctor provides quickly notification +of failure to the VIM, and congress provides proper recovery procedure. In such scheme, +the compute nodes are not recovered by the cluster scheme, but recovered under the +supervision of VIM. + +.. figure:: topology_control_compute.jpg + :alt: HA Deployment Topology of Control Nodes and Compute Nodes + :figclass: align-center + + Fig 2. HA Deployment Topology of Control Nodes and Compute Nodes + +When the cloud is supporting heavy network traffic, which is often the case for the data +plane services in the Telecom scenarios, it is necessary to deploy standalone network +nodes for openstack, so that the large amont of traffic switching and routing will not +bring extra load to the controller nodes. In figure 3, we add network nodes into the +topology and shows how to deploy it in a high available way. In this figure, the +network nodes are deployed in a cluster. The cluster will provide HA for the services +runing on the network nodes. Such cluster scheme could be the same with that of the +compute nodes. + +On thing to be notify is that all hosts in the NFV system should have at least two NICs +that are bonded via LACP. + +.. figure:: topology_control_compute_network.jpg + :alt: HA Deployment Topology of Control Nodes and Compute Nodes and Network Nodes + :figclass: align-center + + Fig 3. HA Deployment Topology of Control Nodes, Compute Nodes and network Nodes + +The HA deployment for storage can be different for all different storage schemes. We will +discuss the detail of the storage HA deployment in section 1.3.3 + +Software HA Framework +================================================================== + +In this section, we introduce more details about the HA schemes for a complete NFV system. + +Openstack Controller services (Openstack services) +-------------------------------------------------------- + +For the High Availability of OpenStack Controller nodes, Pacemaker and Corosync are +often used. The following texts are refering from the HA guideline of OpenStack, which +gives an example of solution of HA deployment.(http://docs.openstack.org/ha-guide/) + +At its core, a cluster is a distributed finite state machine capable of co-ordinating the startup and recovery +of inter-related services across a set of machines. For OpenStack Controller nodes, a cluster management system, +such as Pacemaker, is recommended to use to provide the following metrics. + +1, Awareness of other applications in the stack + +2, Awareness of instances on other machines + +3, A shared implementation and calculation of quorum. + +4, Data integrity through fencing (a non-responsive process does not imply it is not doing anything) + +5, Automated recovery of failed instances + +Figure 4 shows the details of HA schemes for Openstack controller nodes with Pacemaker. + +.. figure:: HA_control.jpg + :alt: HA Deployment of Openstack Control Nodes based on Pacemaker + :figclass: align-center + + Fig 4. HA Deployment of Openstack Control Nodes based on Pacemaker + +High availability of all stateless services are provided by pacemaker and HAProxy. + +Pacemaker cluster stack is the state-of-the-art high availability and load +balancing stack for the Linux platform. Pacemaker is useful to make OpenStack +infrastructure highly available. Also, it is storage and application-agnostic, +and in no way specific to OpenStack. + +Pacemaker relies on the Corosync messaging layer for reliable cluster +communications. Corosync implements the Totem single-ring ordering and +membership protocol. It also provides UDP and InfiniBand based messaging, +quorum, and cluster membership to Pacemaker. + +Pacemaker does not inherently (need or want to) understand the applications +it manages. Instead, it relies on resource agents (RAs), scripts that +encapsulate the knowledge of how to start, stop, and check the health +of each application managed by the cluster.These agents must conform +to one of the OCF, SysV Init, Upstart, or Systemd standards.Pacemaker +ships with a large set of OCF agents (such as those managing MySQL +databases, virtual IP addresses, and RabbitMQ), but can also use any +agents already installed on your system and can be extended with your +own (see the developer guide). + +After deployment of Pacemaker, HAProxy is used to provide VIP for all the +OpenStack services and act as load balancer. HAProxy provides a fast and +reliable HTTP reverse proxy and load balancer for TCP or HTTP applications. +It is particularly suited for web crawling under very high loads while +needing persistence or Layer 7 processing. It realistically supports tens +of thousands of connections with recent hardware. + +Each instance of HAProxy configures its front end to accept connections +only from the virtual IP (VIP) address and to terminate them as a list +of all instances of the corresponding service under load balancing, such +as any OpenStack API service. This makes the instances of HAProxy act +independently and fail over transparently together with the network endpoints +(VIP addresses) failover and, therefore, shares the same SLA. + +We can alternatively use a commercial load balancer, which is a hardware or +software. A hardware load balancer generally has good performance. + +Galera Cluster, or other database cluster service, should also be deployed +to provide data replication and synchronization between data base. Galera +Cluster is a synchronous multi-master database cluster, based on MySQL and +the InnoDB storage engine. It is a high-availability service that provides +high system uptime, no data loss, and scalability for growth. The selection +of DB also will have potential influence on the behaviour on the application +code. For instance using Galera Clusterl may give you higher concurrent write +perfomance but may require a more complex conflict resolution. + +We can also achieve high availability for the OpenStack database in many different +ways, depending on the type of database that we are using. There are three +implementations of Galera Cluster available: + +1, Galera Cluster for MySQL The MySQL reference implementation from Codership; + +2, MariaDB Galera Cluster The MariaDB implementation of Galera Cluster, which is +commonly supported in environments based on Red Hat distributions; + +3, Percona XtraDB Cluster The XtraDB implementation of Galera Cluster from Percona. + +In addition to Galera Cluster, we can also achieve high availability through other +database options, such as PostgreSQL, which has its own replication system. + +To make the RabbitMQ high available, Rabbit HA queue should be configued, and all +openstack services should be configurd to use the Rabbit HA queue. + +In the meantime, specific schemes should also be provided to avoid single point of +failure of Pacemaker. And services failed should be automaticly repaired. + +Note that the scheme we described above is just one possible scheme for the HA +deployment of the controller nodes. Other schemes can also be used to provide cluster +management and monitoring. + +SDN controller services +--------------------------------------- + +SDN controller software is data intensive application. All static and dynamic data has +one or more duplicates distributed to other physical nodes in cluster. Built-in HA schema +always be concordant with data distribution and built-in mechanism will select or +re-select master nodes in cluster. In deployment stage software of SDN controller +should be deployed to at least two or more physical nodes regardless whether the +software is deployed inside VM or containner. Dual management network plane should +be provided for SDN controller cluster to support built-in HA schema. + +Storage +---------------------------------------- +Depending on what storage scheme deployed, different HA schemes should be used. The following +text are refering from the Mirantis OpenStack reference architecture, which provides suggestions +on the HA deployment of different storage schemes. + +1, Ceph + +Ceph implements its own HA. When deploying it, enough controller nodes running the Ceph Monitor +service to form a quarum, and enough Ceph OSD nodes to satisfy the object replication factor are +needed. + +2, Swift + +Swift API relies on the same HAProxy setup with VIP on controller nodes as the other REST +APIs. For small scale deployment, swift storage and Proxy services can be deployed on the +controller nodes. However, for a larger production environment, dedicated storage nodes, in +which two for swift proxy and at least three for swift storage, are needed. + + + +Host OS and Hypervisor +--------------------------------------- + +The Host OS and Hypervisor should be supervised and monitored for failure, and should be +repaired when failure happens. Such supervision can based on a cluster scheme, or can +just simply use controller to constantly monitor the computer host. Figure 6 shows a +simplified framework for hypervisor cluster. + +When host/hypervisor failure happens, VMs on that host should be evacuated. However, +such scheme should coordinate with the VM HA scheme, so that when both the host and the +VM detect the failure, they should know who should take responsibility for the evacuation. + + +.. figure:: HA_Hypervisor.jpg + :alt: HA Deployment of Host OS and Hypervisor + :figclass: align-center + + Fig 5. HA Deployment of Host OS and Hypervisor + +Virtual Machine (VM) +--------------------------------------- + +VM should be supervised and monitored for failure, and should be repaired when failure +happens. We can rely on the hypervisor to monitor the VM failure. Another scheme can be +used is a cluster for the VM, in which failure of VMs in one cluster can be supervised +and will be repaired by the cluster manager. Pacemaker and other cluster management +schemes can be considered for the VM cluster. + +In case when VNFs do not have HA schemes, extra HA scheme for VM should be taken into +consideration. Such approach is kind of best effort for the NFV platform to provide HA +for the VNF service, and may lead to failure copy between VMs when VNF fails. Since the +NFVI can hardly know of the service runing in the VNF, it is imporssible for the NFVI +level to provide overall HA solution for the VNF services. Therefore, even though we +mention this scheme here, we strongly suggest the VNF should have its own HA schemes. + +Figure 6 gives an example for the VM active/standby deployment. In this case, both the +active VM and the standby VM are deployed with the same VNF image. When failure happens +to the active VM, the standby VM should take the traffic and replace the active VM. Such +scheme is the best effort of the NFVI when VNFs do not have HA schemes and would only +rely on VMs to provide redundancy. However, for stateful VNFs, there should be data copy +between the active VM and standby VM. In this case, fault for the active VM can also be +copied to the standby VM, leading to failure of the new active VM. + +.. figure:: images/HA_VM.jpg + :alt: VM Active/Standby Deployment + :figclass: align-center + + Fig 6. VM Active/Standby Deployment + +Virtual Network Functions (VNF) +--------------------------------------- + +For telecom services, it is suggested that VNFs should have its own built-in HA schemes +or HA schemes implemented in VNF Managerhave to provide high available services to +the customers. HA schemes for the VNFs can based on cluster. In this case, OpenSAF, +pacemaker and other cluster management services can be used. + +HA schemes for the VNFs should be coordinate with the lower layer. For example, it +should be clear which level will take responsibility for VM restart. A suggested +schemes could be, the VNF layer should be responsible for the redundancy and failover +of the VNFs when failure happens. Such failover should take place in quite a short +time (less then seconds). The repairing procedure will then take place from upper +layer to lower layer, that is, the VNF layer will first check if the failure is at +its layer, and should try to repair itself. If it fails to repaire the failure, +the failure should escalate to lower layers and let the NFVI layer to do the repair +work. There could also be cases that the NFVI layer has detected the failure and will +repair it before the escalation. These functions should be complished by the coordination +of all different component, including the VNFM, VIM, VNFs and NFVI. + +In the meantime, the VNFs can take advantage of API the hypervisor can provide to +them to enhance HA. Such API may include constant health check from the hypervisor, +affinity/inaffinity deployment support. example about watchdog + +Figure 7 gives an example for the VNF HA scheme. + +.. figure:: HA_VNF.jpg + :alt: HA Deployment of VNFs + :figclass: align-center + + Fig 7. HA Deployment of VNFs + +********************************************************************************* +HA deployment guideline for OPNFV releases +********************************************************************************* + +In this section, we will continiously update the HA deployment guideline for the releases +of OPNFV. + +HA deployment guideline for Arno +============================================== + +Deployment Framework +----------------------------------------------- + +Figure 8 shows an overall architecture for the HA deployment of ARNO. + +For OPNFV Arno release, HA deployment of Openstack Control Node (Openstack Juno) and ODL +controller (ODL Helium) is supported. Both deployment tools (fuel and forman)support +such HA deployment. + +For such HA deployment, the following components¡¯ failure is protected + +Software: +* Nova scheduler +* Nova conductor +* Cinder scheduler +* Neutron server +* Heat engine + +Controller hardware: +* dead server +* dead switch +* dead port +* dead disk +* full disk + +Figure 9 gives an example for the VNF HA scheme. + +.. figure:: HA_ARNO.jpg + :alt: HA Deployment of OPNFV ARNO release + :figclass: align-center + + Fig 9. HA Deployment of OPNFV ARNO release + +HA test result for ARNO +------------------------------------------------- + +Two specific High Availability testcases are done on the ARNO release. These test cases +are collaboratively developed by the High Availability project and the Yardstick project. + +Both cases are excuted in the China Mobile's Lab, where ARNO SR1 release is deployed with +Fuel. + +The two testcases respectively test the following two aspects: + +1, Controll Node Service HA + +In this test, HA of "nova-api" is tested. According to the result, the service can +successfully failover to the other controller nodes within 2.36s, once failure happens +at the active node. However, the service can't repair itself automatically. more +explaination about the repair, other services are not tested yet. + +2, Control Node Hardware HA + +In this test, HA of the controller node hardware is tested. One of the hardware is +abnormally shutdown, and the service of "nova-api" is monitored. According to the test +results, the service can failover to the other controller node within 10.71 secondes. +However, the failed hardware can't automatically repair itself. + +See more details about these test cases in the Yardstick doc of "Test Results for +yardstick-opnfv-ha"(https://gerrit.opnfv.org/gerrit/#/c/7543/). + +From these basic test cases we can see that OPNFV ARNO has integrated with some HA +schemes in its controller nodes. However, its capability of self repair should be +enhanced. + +HA deployment guideline for Brahmaputra +============================================== +In the Brahmaputra release, 4 installers are provided. We will discuss about the HA +deployment of each installer. + +Apex +---------------------------------------------------- + +For the installer of Apex, all of the OpenStack services are in HA on all 3 controllers. +The services are monitored by pacemaker and load balanced by HA Proxy with VIPs. The +SDN controllers usually only run as a single instance on the first controller with no +HA scheme. + +Database is clustered with galera in an active passive failover via pacemaker and the +message bus is rabbitHA and the services are managed by pacemaker. + +Storage is using ceph, clustered across the control nodes. + +In the future, more work is on the way to provide HA for the SDN controller. The Apex +team has already finished a demo that runs ODL on each controller, load balanced to +neutron via a VIP + HA Proxy, but is not using pacemaker. Meanwhile, they are also +working to include ceph storage HA for compute nodes as well. + +Compass +--------------------------------------------------------- +TBD + +Fuel +------------------------------------------------------------- + +At moment Fuel installer support the following HA schemes. + +1)Openstackcontrollers: N-way redundant (1,3,5, etc) +2)OpenDaylight:No redundancy +3)Cephstorage OSD: N-way redundant (1,3,5, etc) +4)Networkingattachment redundancy: LAG +5)NTPredundancy: N-way relays, up to 3 upstream sources +6)DNSredundancy: N-way relays, up to 3 upstream sources +7)DHCP:1+1 + +JOID +--------------------------------------------------------- + +JOID provides HA based on openstack services. Individual service charms have been +deployed in a container within a host, and each charms are distributed in a way each +service which meant for HA will go into container on individual nodes. For example +keystone service, there are three containers on each control node and VIP has been +assigned to use by the front end API to use keystone. So in case any of the container +fails VIP will keep responding to via the other two services. As HA can be maintainer +with odd units at least one service container is required to response. + + +Reference +========== + +* https://www.rdoproject.org/ha/ha-architecture/ +* http://docs.openstack.org/ha-guide/ +* https://wiki.opnfv.org/display/availability?preview=/2926706/2926714/scenario_analysis_for_high_availability_in_nfv.pdf +* https://wiki.opnfv.org/display/availability?preview=/2926706/2926708/ha_requirement.pdf + |