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diff --git a/doc/Escalator_Requirement.rst b/doc/Escalator_Requirement.rst new file mode 100644 index 0000000..e80a11d --- /dev/null +++ b/doc/Escalator_Requirement.rst @@ -0,0 +1,814 @@ +Draft Escalator Requirement v0.4 +================================ + +Authors: +-------- + +| Jie Hu (ZTE, hu.jie@zte.com.cn) +| Qiao Fu (China Mobile, fuqiao@chinamobile.com) +| Ulrich Kleber (Huawei, Ulrich.Kleber@huawei.com) +| Maria Toeroe (Ericsson, maria.toeroe@ericsson.com) +| Sama, Malla Reddy (DOCOMO, sama@docomolab-euro.com) +| Zhong Chao (ZTE, chao.zhong@zte.com.cn) +| Julien Zhang (ZTE, zhang.jun3g@zte.com.cn) +| Yuri Yuan (ZTE, yuan.yue@zte.com.cn) +| Zhipeng Huang (Huawei, huangzhipeng@huawei.com) +| Jia Meng (ZTE, meng.jia@zte.com.cn) +| Liyi Meng (Ericsson, liyi.meng@ericsson.com) +| Pasi Vaananen (Stratus, pasi.vaananen@stratus.com) + +1. Scope +-------- + +| This document describes the user requirements on the smooth upgrade + function of the NFVI and VIM with respect to the upgrades of the OPNFV + platform from one version to another. Smooth upgrade means that the + upgrade results in no service outage for the end-users. This requires + that the process of the upgrade is automatically carried out by a tool + (code name: Escalator) with pre-configured data. The upgrade process + includes preparation, validation, execution, monitoring and + conclusion. +| ==[MT] While it is good to have a tool for the entire upgrade process, + but it is a challenging task, so maybe we shouldn't require automation + for the entire process right away. Automation is essential at + execution.== +| ==[hujie] Maybe we can analysis information flows of the upgrade tool, + abstract the basic / essential actions from the tool (or tools), and + map them to a command set of NFVI / VIM's interfaces.== + +The requirements are defined in a stepwise approach, i.e. in the first +phase focusing on the upgrade of the VIM then widening the scope to the +NFVI. + +The requirements may apply to different NFV functions (NFVI, or VIM, or +both of them) . They will be classified in the Appendix of this +document. + +2. General Requirements Background and terminology +-------------------------------------------------- + +==[MT] At the moment 2.1-2.3 seem to be more background sections than +requirements. Should we rename this part?== + +2.1 Terminologies and definitions +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +- **NFVI** is abbreviation for Network Function Virtualization + Infrastructure; sometimes it is also referred as data plane in this + document. +- **VIM** is abbreviation for Virtual Infrastructure Management; + sometimes it is also referred as control plane in this document. +- **Operators** are network service providers and Virtual Network + Function (VNF) providers. +- **End-Users** are subscribers of Operator's services. +- **Network Service** is a service provided by an Operator to its + End-users using a set of (virtualized) Network Functions +- **Infrastructure Services** are those provided by the NFV + Infrastructure and the Management & Orchestration functions to the + VNFs. I.e. these are the virtual resources as perceived by the VNFs. +- **Smooth Upgrade** means that the upgrade results in no service + outage for the end-users. +- **Rolling Upgrade** is an upgrade strategy that upgrades each node or + a subset of nodes in a wave rolling style through the data centre. It + is a popular upgrade strategy to maintains service availability. +- **Parallel Universe** is an upgrade strategy that creates and deploys + a new universe - a system with the new configuration - while the old + system continues running. The state of the old system is transferred + to the new system after sufficient testing of the later. +- **Infrastructure Resource Model** ==(suggested by MT)== is identified + as: physical resources, virtualization facility resources and virtual + resources. +- **Physical Resources** are the hardware of the infrastructure, may + also includes the firmware that enable the hardware. +- **Virtual Resources** are resources provided as services built on top + of the physical resources via the virtualization facilities; in our + case, they are the components that VNF entities are built on, e.g. + the VMs, virtual switches, virtual routers, virtual disks etc + ==[MT] I don't think the VNF is the virtual resource. Virtual + resources are the VMs, virtual switches, virtual routers, virtual + disks etc. The VNF uses them, but I don't think they are equal. The + VIM doesn't manage the VNF, but it does manage virtual resources.== +- **Visualization Facilities** are resources that enable the creation + of virtual environments on top of the physical resources, e.g. + hypervisor, OpenStack, etc. + +2.2 Upgrade Objects +~~~~~~~~~~~~~~~~~~~ + +2.2.1 Physical Resource +^^^^^^^^^^^^^^^^^^^^^^^ + +| Most of the cloud infrastructures support dynamic addition/removal of + hardware. A hardware upgrade could be done by removing the old + hardware node and adding the new one. This will not be in the scope of + this project. +| ==[MT] Does this mean that we are excluding firmware upgrades too?== + +2.2.2 Virtual Resources +^^^^^^^^^^^^^^^^^^^^^^^ + +| Virtual resource upgrade mainly done by users. OPNFV may facilitate + the activity, but suggest to have it in long term roadmap instead of + initiate release. +| ==[MT] same comment here: I don't think the VNF is the virtual + resource. Virtual resources are the VMs, virtual switches, virtual + routers, virtual disks etc. The VNF uses them, but I don't think they + are equal. For example if by some reason the hypervisor is changed and + the current VMs cannot be migrated to the new hypervisor, they are + incompatible, then the VMs need to be upgraded too. This is not + something the NFVI user (i.e. VNFs ) would even know about.== + +2.2.3 Virtualization Facility Resources +^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ + +| Based on the functionality they provide, virtualization facility + resources could be divided into computing node, networking node, + storage node and management node. +| The possible upgrade objects in these nodes are addressed below: + (Note: hardware based virtualization may considered as virtualization + facility resource, but from escalator perspective, it is better + considered it as part of hardware upgrade. ) + +**Computing node** + +#. OS Kernel +#. Hypvervisor and virtual switch +#. Other kernel modules, like driver +#. User space software packages, like nova-compute agents and other + control plane programs + +| Updating 1 and 2 will cause the loss of virtualzation functionality of + the compute node, which may lead to data plane services interruption + if the virtual resource is not redudant. +| Updating 3 might result the same. +| Updating 4 might lead to control plane services interruption if not an + HA deployment. + +**Networking node** + +#. OS kernel, optional, not all switch/router allow you to upgrade its + OS since it is more like a firmware than a generic OS. +#. User space software package, like neutron agents and other control + plane programs + +| Updating 1 if allowed will cause a node reboot and therefore leads to + data plane services interruption if the virtual resource is not + redudant. +| Updating 2 might lead to control plane services interruption if not an + HA deployment. + +**Storage node** + +#. OS kernel, optional, not all storage node allow you to upgrade its OS + since it is more like a firmware than a generic OS. +#. Kernel modules +#. User space software packages, control plane programs + +| Updating 1 if allowed will cause a node reboot and therefore leads to + data plane services interruption if the virtual resource is not + redudant. +| Update 2 might result in the same. +| Updating 3 might lead to control plane services interruption if not an + HA deployment. + +**Management node** + +#. OS Kernel +#. Kernel modules, like driver +#. User space software packages, like database, message queue and + control plane programs. + +| Updating 1 will cause a node reboot and therefore leads to control + plane services interruption if not an HA deployment. Updating 2 might + result in the same. +| Updating 3 might lead to control plane services interruption if not an + HA deployment. + +2.3 Upgrade Span +~~~~~~~~~~~~~~~~ + +| **Major Upgrade** +| Upgrades between major releases may introducing significent changes in + function, configuration and data, such as the upgrade of OPNFV from + Arno to Brahmaputra. + +| **Minor Upgrade** +| Upgrades inside one major releases which would not leads to changing + the stucture of the platform and may not infect the schema of the + system data. + +2.4 Upgrade Granularity +~~~~~~~~~~~~~~~~~~~~~~~ + +2.4.1 Physical/Hardware Dimension +^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ + +Support full / partial upgrade for data centre, cluster, zone. Because +of the upgrade of a data centre or a zone, it may be divided into +several batches. The upgrade of a cloud environment (cluster) may also +be partial. For example, in one cloud environment running a number of +VNFs, we may just try one of them to check the stability and +performance, before we upgrade all of them. + +2.4.2 Software Dimension +^^^^^^^^^^^^^^^^^^^^^^^^ + +- The upgrade of host OS or kernel may need a 'hot migration' +- The upgrade of OpenStack’s components + i.the one-shot upgrade of all components + ii.the partial upgrade (or bugfix patch) which only affects some + components (e.g., computing, storage, network, database, message + queue, etc.) + +| ==[MT] this section seems to overlap with 2.1.== +| I can see the following dimensions for the software + +- different software packages +- different funtions - Considering that the target versions of all + software are compatible the upgrade needs to ensure that any + dependencies between SW and therefore packages are taken into account + in the upgrade plan, i.e. no version mismatch occurs during the + upgrade therefore dependencies are not broken +- same function - This is an upgrade specific question if different + versions can coexist in the system when a SW is being upgraded from + one version to another. This is particularly important for stateful + functions e.g. storage, networking, control services. The upgrade + method must consider the compatibility of the redundant entities. + +- different versions of the same software package +- major version changes - they may introduce incompatibilities. Even + when there are backward compatibility requirements changes may cause + issues at graceful rollback +- minor version changes - they must not introduce incompatibility + between versions, these should be primarily bug fixes, so live + patches should be possible + +- different installations of the same software package +- using different installation options - they may reflect different + users with different needs so redundancy issues are less likely + between installations of different options; but they could be the + reflection of the heterogeneous system in which case they may provide + redundancy for higher availability, i.e. deeper inspection is needed +- using the same installation options - they often reflect that the are + used by redundant entities across space + +- different distribution possibilities in space - same or different + availability zones, multi-site, geo-redundancy + +- different entities running from the same installation of a software + package +- using different startup options - they may reflect different users so + redundancy may not be an issues between them +- using same startup options - they often reflect redundant + entities==== + +3.5 Upgrade duration +~~~~~~~~~~~~~~~~~~~~ + +As the OPNFV end-users are primarily Telco operators, the network +services provided by the VNFs deployed on the NFVI should meet the +requirement of 'Carrier Grade'. + +In telecommunication, a "carrier grade" or"carrier class" refers to a +system, or a hardware or software component that is extremely reliable, +well tested and proven in its capabilities. Carrier grade systems are +tested and engineered to meet or exceed "five nines" high availability +standards, and provide very fast fault recovery through redundancy +(normally less than 50 milliseconds). [from wikipedia.org] + +"five nines" means working all the time in ONE YEAR except 5'15". + +We have learnt that a well prepared upgrade of OpenStack needs 10 +minutes. The major time slot in the outage time is used spent on +synchronizing the database. [from ' Ten minutes OpenStack Upgrade? Done! +' by Symantec] + +This 10 minutes of downtime of OpenStack however did not impact the +users, i.e. the VMs running on the compute nodes. This was the outage of +the control plane only. On the other hand with respect to the +preparations this was a manually tailored upgrade specific to the +particular deployment and the versions of each OpenStack service. + +The project targets to achieve a more generic methodology, which however +requires that the upgrade objects fulfill ceratin requirements. Since +this is only possible on the long run we target first upgrades from +version to version for the different VIM services. + +**Questions:** + +#. | Can we manage to upgrade OPNFV in only 5 minutes? + | ==[MT] The first question is whether we have the same carrier grade + requirement on the control plane as on the user plane. I.e. how + much control plane outage we can/willing to tolerate? + | In the above case probably if the database is only half of the size + we can do the upgrade in 5 minutes, but is that good? It also means + that if the database is twice as much then the outage is 20 + minutes. + | For the user plane we should go for less as with two release yearly + that means 10 minutes outage per year.== + | ==[Malla] 10 minutes outage per year to the users? Plus, if we take + control plane into the consideration, then total outage will be + more than 10 minute in whole network, right?== + | ==[MT] The control plane outage does not have to cause outage to + the users, but it may of course depending on the size of the system + as it's more likely that there's a failure that needs to be handled + by the control plane.== + +#. | Is it acceptable for end users ? Such as a planed service + interruption will lasting more than ten minutes for software + upgrade. + | ==[MT] For user plane, no it's not acceptable in case of + carrier-grade. The 5' 15" downtime should include unplanned and + planned downtimes.== + | ==[Malla] I go agree with Maria, it is not acceptable.== + +#. | Will any VNFs still working well when VIM is down? + | ==[MT] In case of OpenStack it seems yes. .:)== + +2.5.1 The maximum duration of an upgrade +^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ + +| The duration of an upgrade is related to and proportional with the + scale and the complexity of the OPNFV platform as well as the + granularity (in function and in space) of the upgrade. +| [Malla] Also, if is a partial upgrade like module upgrade, it depends + also on the OPNFV modules and their tight connection entites as well. + +2.5.2 The maximum duration of a rollback when an upgrade is failed - this should be about rollback duration +^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ + +| The duration of a rollback is short than the corresponding upgrade. It + depends on the duration of restore the software and configue data from + pre-upgrade backup / snapshot. +| ==[MT] During the upgrade process two types of failure may happen: +| In case we can recover from the failure by undoing the upgrade + actions it is possible to roll back the already executed part of the + upgrade in graceful manner introducing no more service outage than + what was introduced during the upgrade. Such a graceful rollback + requires typically the same amount of time as the executed portion of + the upgrade and impose minimal state/data loss.== +| ==[MT] Requirement: It should be possible to roll back gracefully the + failed upgrade of stateful services of the control plane. +| In case we cannot recover from the failure by just undoing the + upgrade actions, we have to restore the upgraded entities from their + backed up state. In other terms the system falls back to an earlier + state, which is typically a faster recovery procedure than graceful + rollback and depending on the statefulness of the entities involved it + may result in significant state/data loss.== +| **Two possible types of failures can happen during an upgrade** + +#. We can recover from the failure that occured in the upgrade process: + In this case, a graceful rolling back of the executed part of the + upgrade may be possible which would "undo" the executed part in a + similar fashion. Thus, such a roll back introduces no more service + outage during an upgrade than the executed part introduced. This + process typically requires the same amount of time as the executed + portion of the upgrade and impose minimal state/data loss. +#. We cannot recover from the failure that occured in the upgrade + process: In this case, the system needs to fall back to an earlier + consistent state by reloading this backed-up state. This is typically + a faster recovery procedure than the graceful rollback, but can cause + state/data loss. The state/data loss usually depends on the + statefulness of the entities whose state is restored from the backup. + +2.5.3 The maximum duration of a VNF interruption +^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ + +| Since not the entire process of a smooth upgrade will affect the VNFs, + the duration of the VNF interruption may be shorter than the duration + of the upgrade. In some cases, the VNF running without the control + from of the VIM is acceptable. +| ==[MT] Should require explicitly that the NFVI should be able to + provide its services to the VNFs independent of the control plane?== +| ==[MT] Requirement: The upgrade of the control plane must not cause + interruption of the NFVI services provided to the VNFs.== +| ==[MT] With respect to carrier-grade the yearly service outage of the + VNF should not exceed 5' 15" regardless whether it is planned or + unplanned outage. Considering the HA requirements TL-9000 requires an + ent-to-end service recovery time of 15 seconds based on which the ETSI + GS NFV-REL 001 V1.1.1 (2015-01) document defines three service + availability levels (SAL). The proposed example service recovery times + for these levels are: +| SAL1: 5-6 seconds +| SAL2: 10-15 seconds +| SAL3: 20-25 seconds== +| ==[Pva] my comment was actually that the downtime metrics of the + underlying elements, components and services are small fraction of the + total E2E service availability time. No-one on the E2E service path + will get the whole downtime allocation (in this context it includes + upgrade process related outages for the services provided by VIM etc. + elements that are subject to upgrade process).== +| ==[MT] So what you are saying is that the upgrade of any entity + (component, service) shouldn't cause even this much service + interruption. This was the reason I brought these figures here as well + that they are posing some kind of upper-upper boundary. Ideally the + interruption is in the millisecond range i.e. no more than a + switchover or a live migration.== +| ==[MT] Requirement: Any interruption caused to the VNF by the upgrade + of the NFVI should be in the sub-second range.== + +==[MT] In the future we also need to consider the upgrade of the NFVI, +i.e. HW, firmware, hypervisors, host OS etc.== + +3. Functional Considerations +---------------------------- + +3.1 Requirement of Escalator's Basic Actions +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +This section describes the basic functions may required by Escalator. + +3.1.1 Preparation (offline) +^^^^^^^^^^^^^^^^^^^^^^^^^^^ + +This is the design phase when the upgrade plan (or upgrade campaign) is +being designed so that it can be executed automatically with minimal +service outage. It may include the following work: + +#. Check the dependencies of the software modules and their impact, + backward compatibilities to figure out the appropriate upgrade method + and ordering. +#. Find out if a rolling upgrade could be planned with several rolling + steps to avoid any service outage due to the upgrade some + parts/services at the same time. +#. Collect the proper version files and check the integration for + upgrading. +#. The preparation step should produce an output (i.e. upgrade + campaign/plan), which is executable automatically in an NFV Famawork + and which can be validated before execution. + + - The upgrade campaign should not be referring to scalable entities + directly, but allow for adaptation to the system configuration and + state at any given moment. + - The upgrade campaign should describe the ordering of the upgrade + of different entities so that dependencies, redundancies can be + maintained during the upgrade execution + - The upgrade campaign should provide information about the + applicable recovery procedures and their ordering. + - The upgrade campaign should consider information about the + verification/testing procedures to be performed during the upgrade + so that upgrade failures can be detected as soon as possible and + the appropriate recovery procedure can be identified and applied. + - The upgrade campaign should provide information on the expected + execution time so that hanging execution can be identified + - The upgrade campaign should indicate any point in the upgrade when + coordination with the users (VNFs) is required. + +==[hujie]Depends on the attributes of the object being upgraded, the +upgrade plan may be slitted into step(s) and/or sub-plan(s), and even +more small sub-plans in design phase. The plan(s) or sub-plan(s) my +include step(s) or sub-plan(s).== + +3.1.2 Validation the upgrade plan / Checking the pre-requisites of System( offline / online) +^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ + +| The upgrade plan should be validated before the execution by testing + it in a test environment which is similar to the product environment. +| ==[MT]However it could also mean that we can identify some properties + that it should satisfy e.g. what operations can or cannot be executed + simultaneously like never take out two VMs of the same VNF. +| Another question is if it requires that the system is in a particular + state when the upgrade is applied. I.e. if there's certain amount of + redundacy in the system, migration is enabled for VMs, when the NFVI + is upgraded the VIM is healthy, when the VIM is upgraded the NFVI is + healthy, etc. +| I'm not sure what online validation means: Is it the validation of the + upgrade plan/campaign or the validation of the system that it is in a + state that the upgrade can be performed without too much risk?== + +| Before the upgrade plan being executed, the system heathly of the + online product environment should be checked and confirmed to satisfy + the requirements which were described in the upgrade plan. The + sysinfo, e.g. which included system alarms, performance statistics and + diagnostic logs, will be collected and analyized. It is required to + resolve all of the system faults or exclud the unhealthy part before + executing the upgrade plan. +| ==[hujie] Text merged.== + +3.1.3 Backup/Snapshot (online) +^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ + +For avoid loss of data when a unsuccessful upgrade was encountered, the +data should be backuped and the system state snapshot should be taken +before the excution of upgrade plan. This would be considered in the +upgrade plan. + +Several backups/Snapshots may be generated and stored before the single +steps of changes. The following data/files are required to be +considered: + +#. running version files for each node. +#. system components' configuration file and database. +#. image and storage, if it is necessary. + ==[MT] Does 3 imply VNF image and storage? I.e. VNF state and data?== + +| ==[hujie] The following text is derived from previous "4. Negotiate + with the VNF if it's ready for the upgrade"== +| Although the upper layer, which include VNFs and VNFMs, is out of the + scope of Escalator, but it is still recommended to let it ready for a + smooth system upgrade. The escalator could not garanttee the safe of + VNFs. The upper layer should have some safe guard mechanism in design, + and ready for avoiding failure in system upgrade. + +3.1.4 Execution (online) +^^^^^^^^^^^^^^^^^^^^^^^^ + +| The execution of upgrade plan should be a dynamical procedure which is + controlled by Escalator. +| ==[hujie] Revised text to be general.== + +#. It is required to supporting execution ether in sequence or in + parallel. +#. It is required to checke the result of the execution and take the + action according the situation and the policies in the upgrade plan. +#. It is required to execute properly on various configurations of + system object. I.e. stand-alone, HA, etc. +#. It is required to excecute on the designated different parts of the + system. I.e. physical server, virtualized server, rack, chassis, + cluster, even different geographical places. + +3.1.5 Testing (online) +^^^^^^^^^^^^^^^^^^^^^^ + +| The testing after upgrade the whole system or parts of system to make + sure the upgraded system(object) is working normally. +| ==[hujie] Revised text to be general.== + +#. It is recommended to run the prepared test cases to see if the + functionalities are availiable without any problem. +#. It is recommended to check the sysinfo, e.g. system alarms, + performance statistics and diagnostic logs to see if there are any + abnormal. + +3.1.6 Restore/Rollback (online) +^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ + +| When upgrade is failure unfortunatly, a quick system restore or system + rollback should be taken to recovery the system and the services. +| ==[hujie] Revised text to be general.== + +#. It is recommend to support system restore from backup when upgrade + was failed. +#. It is recommend to support gracefull rollback with reverse order + steps if possible. + +3.1.7 Monitoring (online) +^^^^^^^^^^^^^^^^^^^^^^^^^ + +| Escalator should continually monitor the process of upgrade. It is + keeping update status of each module, each node, each cluster into a + status table during upgrade. +| ==[hujie] Revised text to be general.== + +#. It is required to collect the status of every objects being upgraded + and sending abnormal alerms during the upgrade. +#. It is recommend to reuse the existing monitoring system, like alarm. +#. It is recommend to support pro-actively query. +#. It is recommend to support passively wait for notification. + +| **Two possible ways for monitoring:** +| **Pro-Actively Query** requires NFVI/VIM provides proper API or CLI + interface. If Escalator serves as a service, it should pass on these + interfaces. +| **Passively Wait for Notification** requires Escalator provides + callback interface, which could be used by NFVI/VIM systems or upgrade + agent to send back notification. +| [hujie] I am not sure why not to subscribe the notification. + +3.1.8 Logging (online) +^^^^^^^^^^^^^^^^^^^^^^ + +Record the information generated by escalator into log files. The log +file is used for manual diagnostic of exceptions. + +#. It is required to support logging. +#. It is recommended to include time stamp, object id, action name, + error code, etc. + +3.1.9 Administrative Control (online) +^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ + +Administrative Control is used for control the privilege to start any +escalator's actions for avoding unauthorized operations. + +#. It is required to support administrative control mechenism +#. It is recommed to reuse the system's own secure system. +#. It is required to avoid conflicts when the system's own secure system + being upgraded. + +3.2 Requirements on system object being upgraded +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +| ==We can develope BPs in future from req of this section and GA for + upper stream projects== +| Escalator focus on smooth upgrade. In practical implementation, it + might be combined with installer/deployer, or act as an independent + tool/service. In either way, it requires targeting systems(NFVI and + VIM) are developed/deployed in a way that Escalator could perform + upgrade on them. + +On NFVI system, live-migration is likely used to maintain availability +because OPNFV would like to make HA transparent from end user. This +requires VIM system being able to put compute node into maintenance mode +and then isolated from normal service. Otherwise, new NFVI instances +might risk at being schedule into the upgrading node. + +| On VIM system, availability is likely achieved by redundancy. This + impose less requirements on system/services being upgrade (see PVA + comments in early version). However, there should be a way to put the + target system into standby mode. Because starting upgrade on the + master node in a cluster is likely a bad idea. +| ==[hujie] Revised text to be general.== + +#. It is required for NFVI/VIM to support **service handover** mechanism + that minimize interruption to 0.001%(i.e. 99.999% service + availability). Possible implementations are live-migration, redundant + deployment, etc, (Note: for VIM, interruption could be less + restrictive) +#. It is required for NFVI/VIM to restore the early verion in a efficent + way, such as **snapshot**. +#. It is required for NFVI/VIM to **migration data** efficiently between + base and upgraded system. + ==[hujie] What is exact meaning of "base" here?== +#. It is recomend for NFV/VIM's interface to support upgrade + orchestration, e.g. reading/setting system state + ==[hujie] I am not sure if it reflect the previous text.== + +4. Use Cases +------------ + +This section describes the use cases to verify the requirements of +Escalator. + +4.1 Upgrade a system with minimal configuration +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +A minimal configuration system is normally depolyed for experimental or +developement ussage, such as a OPNFV test bed. Althouth it dose not have +large workload, but it is a typical system to be upgraded frequently. + +4.2 Upgrade a system with HA configuration +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +A HA configuration system is very popular in the operator's data centre. +And it is a typical product environment. It always running 7 \* 24 a +week with VNFs running on it to provide services to the end users. + +4.3 Upgrade a system with Multi-Site configuration +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +Upgrade in one site may cause service interruption to other site, if +both sites are depended and sharing the same modules/data base (e.g. a +keystone for both sites). + +If a site failure during an upgrade, the rollback missing any minimal +state/data loss can cause an affect/failure to the depended site. + +==Consider one site of ARNO release first. Then, multi-site in the +future.== + +5. RA of Escalator +------------------ + +This section describes the reference architecture, the function blocks, +the function entities of Escalator for the reader to well understand how +the basic functions be organized. + +6. Information Flows +-------------------- + +| This section describes the information flows among the function + entities when Escalator is in actions. +| We should consider a generic procedure / frameworks of upgrading. And + may provide a plugin interface for specialized tasks + +7. Interfaces +------------- + +This section describes the required interfaces of Escalator. + +7.1 Manual Interface (CLI / GUI) +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +7.2 RESTful API +~~~~~~~~~~~~~~~ + +To support 3.3 Negotiate with the VNF if it's ready for the upgrade + +7.3 Configuration File +~~~~~~~~~~~~~~~~~~~~~~ + +This section will suggest a format of the configuration files and how to +deal with it. + +7.4 Log File +------------ + +This section will suggest a format of the log files and how to deal with +it. + +8. Requirements from other OPNFV projects +----------------------------------------- + +| We have created a questionnaire for collecting other projects + requirments + (https://docs.google.com/forms/d/11o1mt15zcq0WBtXYK0n6lKF8XuIzQTwvv8ePTjmcoF0/viewform?usp=send_form), + please advertise it. +| ==[hujie] Can we force other OPNFV projects to complete the survey by + using JIRA dependence?== + +8.1 Doctor Project +~~~~~~~~~~~~~~~~~~ + +| ==Note: This scenario could be out of scope in Escalator project, but + having the option to support this should be better to align with + Doctor requirements.== +| The scope of Doctor project also covers maintenance scenario in which + 1) the VIM administorator requests host maintenance to VIM, 2) VIM + will notifiy it to consumer such as VNFM to trigger application level + migration or switching active-standby nodes, and 3) VIM waits responce + from the consumer for a short while. + +- VIM should send out notification of VM migration to consumer (VNFM) + as abstracted message like "maintenance". +- VIM could wait VM migration until it receives "VM ready to + maintenance" message from the owner (VNFM) + +8.2 HA Project +~~~~~~~~~~~~~~ + +8.3 Multi-site Project +~~~~~~~~~~~~~~~~~~~~~~ + +- Escalator upgrade one site should at least not lead to the other site + API token validation failed. + +9. Reference +------------ + +| [1] ETSI GS NFV 002 (V1.1.1): “Architectural Framework” +| [2] ETSI GS NFV 003 (V1.1.1): "Terminology for Main Concepts in NFV". +| [3] ETSI GS NFV-SWA001:“Virtual Network Function Architecture” +| [4] ETSI GS NFV-MAN001:“Management and Orchestration” +| [5] ETSI GS NFV-REL001:"Resiliency Requirements" +| [6] QuEST Forum TL-9000:"Quality Management System Requirement + Handbook" +| [7] Service Availabilty Forum AIS:"Software Management Framework" + +10. Useful Working Drafts of ETSI NFV +------------------------------------- + +| Access them with your own ETSI account, please DO NOT disclose the + content. +| [1] Migrate Virtualised Compute Resource operation @ 7.3.1.8 +| ftp://docbox.etsi.org/ISG/NFV/Open/Drafts/IFA005_Or-Vi_ref_point_Spec/NFV-IFA005v070.zip +| [2] Reliability issues during NFV Software upgrade and improvement + mechanisms @ 8 +| ftp://@docbox.etsi.org/ISG/NFV/Open/Drafts/REL003_E2E_reliability_models/NFV-REL003v030.zip + +Appendix +-------- + +A.1 Impact Analysis +~~~~~~~~~~~~~~~~~~~ + +Upgrading the different software modules may cause different impact on +the availability of the infrastracture resources and even on the service +continuity of the vNFs. + +**Software modules in the computing nodes** + +#. Host OS patch + ==[MT] As SW module, we should list the host OS and maybe ====its + drivers as well. From upgrade persepctive do we limit host OS + upgrades to patches only?== +#. Hypervisor, such as KVM, QEMU, XEN, libvirt +#. Openstack agent in computing nodes (like Nova agent, Ceilometer + agent...) + +**Software modules in network nodes** + +#. Neutron L2/L3 agent +#. OVS, SR-IOV Driver + +**Software modules storage nodes** + +#. Ceph + +The table below analyses such an impact - considering a single instance +of each software module - from the following aspects: + +- the function which will be lost during upgrade, +- the duration of the loss of this specific function, +- if this causes the loss of the vNF function, +- if it causes incompatibility in the different parts of the software, +- what should be backed up before the upgrade, +- the duration of restoration time if the upgrade fails + +| These values provided come from internal testing and based on some + assumptions, they may vary depending on the deployment techniques. + Please feel free to add if you find more efficient values during your + testing. +| https://wiki.opnfv.org/_media/upgrade_analysis_v0.5.xlsx +| Note that no redundancy of the software modules is considered in the + table. |