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diff --git a/docs/development/requirements/04-gaps.rst b/docs/development/requirements/04-gaps.rst new file mode 100644 index 00000000..b8ff7f2e --- /dev/null +++ b/docs/development/requirements/04-gaps.rst @@ -0,0 +1,389 @@ +.. This work is licensed under a Creative Commons Attribution 4.0 International License. +.. http://creativecommons.org/licenses/by/4.0 + +Gap analysis in upstream projects +================================= + +This section presents the findings of gaps on existing VIM platforms. The focus +was to identify gaps based on the features and requirements specified in Section +3.3. The analysis work determined gaps that are presented here. + +VIM Northbound Interface +------------------------ + +Immediate Notification +^^^^^^^^^^^^^^^^^^^^^^ + +* Type: 'deficiency in performance' +* Description + + + To-be + + - VIM has to notify unavailability of virtual resource (fault) to VIM user + immediately. + - Notification should be passed in '1 second' after fault detected/notified + by VIM. + - Also, the following conditions/requirement have to be met: + + - Only the owning user can receive notification of fault related to owned + virtual resource(s). + + + As-is + + - OpenStack Metering 'Ceilometer' can notify unavailability of virtual + resource (fault) to the owner of virtual resource based on alarm + configuration by the user. + + - Ceilometer Alarm API: + http://docs.openstack.org/developer/ceilometer/webapi/v2.html#alarms + + - Alarm notifications are triggered by alarm evaluator instead of + notification agents that might receive faults + + - Ceilometer Architecture: + http://docs.openstack.org/developer/ceilometer/architecture.html#id1 + + - Evaluation interval should be equal to or larger than configured pipeline + interval for collection of underlying metrics. + + - https://github.com/openstack/ceilometer/blob/stable/juno/ceilometer/alarm/service.py#L38-42 + + - The interval for collection has to be set large enough which depends on + the size of the deployment and the number of metrics to be collected. + - The interval may not be less than one second in even small deployments. + The default value is 60 seconds. + - Alternative: OpenStack has a message bus to publish system events. + The operator can allow the user to connect this, but there are no + functions to filter out other events that should not be passed to the user + or which were not requested by the user. + + + Gap + + - Fault notifications cannot be received immediately by Ceilometer. + +* Solved by + + + Event Alarm Evaluator: + https://specs.openstack.org/openstack/ceilometer-specs/specs/liberty/event-alarm-evaluator.html + + New OpenStack alarms and notifications project AODH: + http://docs.openstack.org/developer/aodh/ + +Maintenance Notification +^^^^^^^^^^^^^^^^^^^^^^^^ + +* Type: 'missing' +* Description + + + To-be + + - VIM has to notify unavailability of virtual resource triggered by NFVI + maintenance to VIM user. + - Also, the following conditions/requirements have to be met: + + - VIM should accept maintenance message from administrator and mark target + physical resource "in maintenance". + - Only the owner of virtual resource hosted by target physical resource + can receive the notification that can trigger some process for + applications which are running on the virtual resource (e.g. cut off + VM). + + + As-is + + - OpenStack: None + - AWS (just for study) + + - AWS provides API and CLI to view status of resource (VM) and to create + instance status and system status alarms to notify you when an instance + has a failed status check. + http://docs.aws.amazon.com/AWSEC2/latest/UserGuide/monitoring-instances-status-check_sched.html + - AWS provides API and CLI to view scheduled events, such as a reboot or + retirement, for your instances. Also, those events will be notified + via e-mail. + http://docs.aws.amazon.com/AWSEC2/latest/UserGuide/monitoring-system-instance-status-check.html + + + Gap + + - VIM user cannot receive maintenance notifications. + +* Solved by + + + https://blueprints.launchpad.net/nova/+spec/service-status-notification + +VIM Southbound interface +------------------------ + +Normalization of data collection models +^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ + +* Type: 'missing' +* Description + + + To-be + + - A normalized data format needs to be created to cope with the many data + models from different monitoring solutions. + + + As-is + + - Data can be collected from many places (e.g. Zabbix, Nagios, Cacti, + Zenoss). Although each solution establishes its own data models, no common + data abstraction models exist in OpenStack. + + + Gap + + - Normalized data format does not exist. + +* Solved by + + + Specification in Section :ref:`southbound`. + +OpenStack +--------- + +Ceilometer +^^^^^^^^^^ + +OpenStack offers a telemetry service, Ceilometer, for collecting measurements of +the utilization of physical and virtual resources [CEIL]_. Ceilometer can +collect a number of metrics across multiple OpenStack components and watch for +variations and trigger alarms based upon the collected data. + +Scalability of fault aggregation +________________________________ + +* Type: 'scalability issue' +* Description + + + To-be + + - Be able to scale to a large deployment, where thousands of monitoring + events per second need to be analyzed. + + + As-is + + - Performance issue when scaling to medium-sized deployments. + + + Gap + + - Ceilometer seems to be unsuitable for monitoring medium and large scale + NFVI deployments. + +* Solved by + + + Usage of Zabbix for fault aggregation [ZABB]_. Zabbix can support a much + higher number of fault events (up to 15 thousand events per second, but + obviously also has some upper bound: + http://blog.zabbix.com/scalable-zabbix-lessons-on-hitting-9400-nvps/2615/ + + + Decentralized/hierarchical deployment with multiple instances, where one + instance is only responsible for a small NFVI. + +Monitoring of hardware and software +___________________________________ + +* Type: 'missing (lack of functionality)' +* Description + + + To-be + + - OpenStack (as VIM) should monitor various hardware and software in NFVI to + handle faults on them by Ceilometer. + - OpenStack may have monitoring functionality in itself and can be + integrated with third party monitoring tools. + - OpenStack need to be able to detect the faults listed in the Annex. + + + As-is + + - For each deployment of OpenStack, an operator has responsibility to + configure monitoring tools with relevant scripts or plugins in order to + monitor hardware and software. + - OpenStack Ceilometer does not monitor hardware and software to capture + faults. + + + Gap + + - Ceilometer is not able to detect and handle all faults listed in the Annex. + +* Solved by + + + Use of dedicated monitoring tools like Zabbix or Monasca. + See :ref:`nfvi_faults`. + +Nova +^^^^ + +OpenStack Nova [NOVA]_ is a mature and widely known and used component in +OpenStack cloud deployments. It is the main part of an +"infrastructure-as-a-service" system providing a cloud computing fabric +controller, supporting a wide diversity of virtualization and container +technologies. + +Nova has proven throughout these past years to be highly available and +fault-tolerant. Featuring its own API, it also provides a compatibility API with +Amazon EC2 APIs. + +Correct states when compute host is down +________________________________________ + +* Type: 'missing (lack of functionality)' +* Description + + + To-be + + - The API shall support to change VM power state in case host has failed. + - The API shall support to change nova-compute state. + - There could be single API to change different VM states for all VMs + belonging to a specific host. + - Support external systems that are monitoring the infrastructure and resources + that are able to call the API fast and reliable. + - Resource states are reliable such that correlation actions can be fast and automated. + - User shall be able to read states from OpenStack and trust they are correct. + + + As-is + + - When a VM goes down due to a host HW, host OS or hypervisor failure, + nothing happens in OpenStack. The VMs of a crashed host/hypervisor are + reported to be live and OK through the OpenStack API. + - nova-compute state might change too slowly or the state is not reliable + if expecting also VMs to be down. This leads to ability to schedule VMs + to a failed host and slowness blocks evacuation. + + + Gap + + - OpenStack does not change its states fast and reliably enough. + - The API does not support to have an external system to change states and to + trust the states are reliable (external system has fenced failed host). + - User cannot read all the states from OpenStack nor trust they are right. + +* Solved by + + + https://blueprints.launchpad.net/nova/+spec/mark-host-down + + https://blueprints.launchpad.net/python-novaclient/+spec/support-force-down-service + +Evacuate VMs in Maintenance mode +________________________________ + +* Type: 'missing' +* Description + + + To-be + + - When maintenance mode for a compute host is set, trigger VM evacuation to + available compute nodes before bringing the host down for maintenance. + + + As-is + + - If setting a compute node to a maintenance mode, OpenStack only schedules + evacuation of all VMs to available compute nodes if in-maintenance compute + node runs the XenAPI and VMware ESX hypervisors. Other hypervisors (e.g. + KVM) are not supported and, hence, guest VMs will likely stop running due + to maintenance actions administrator may perform (e.g. hardware upgrades, + OS updates). + + + Gap + + - Nova libvirt hypervisor driver does not implement automatic guest VMs + evacuation when compute nodes are set to maintenance mode (``$ nova + host-update --maintenance enable <hostname>``). + +Monasca +^^^^^^^ + +Monasca is an open-source monitoring-as-a-service (MONaaS) solution that +integrates with OpenStack. Even though it is still in its early days, it is the +interest of the community that the platform be multi-tenant, highly scalable, +performant and fault-tolerant. It provides a streaming alarm engine, a +notification engine, and a northbound REST API users can use to interact with +Monasca. Hundreds of thousands of metrics per second can be processed +[MONA]_. + +Anomaly detection +_________________ + + +* Type: 'missing (lack of functionality)' +* Description + + + To-be + + - Detect the failure and perform a root cause analysis to filter out other + alarms that may be triggered due to their cascading relation. + + + As-is + + - A mechanism to detect root causes of failures is not available. + + + Gap + + - Certain failures can trigger many alarms due to their dependency on the + underlying root cause of failure. Knowing the root cause can help filter + out unnecessary and overwhelming alarms. + +* Status + + + Monasca as of now lacks this feature, although the community is aware and + working toward supporting it. + +Sensor monitoring +_________________ + +* Type: 'missing (lack of functionality)' +* Description + + + To-be + + - It should support monitoring sensor data retrieval, for instance, from + IPMI. + + + As-is + + - Monasca does not monitor sensor data + + + Gap + + - Sensor monitoring is very important. It provides operators status + on the state of the physical infrastructure (e.g. temperature, fans). + +* Addressed by + + + Monasca can be configured to use third-party monitoring solutions (e.g. + Nagios, Cacti) for retrieving additional data. + +Hardware monitoring tools +------------------------- + +Zabbix +^^^^^^ + +Zabbix is an open-source solution for monitoring availability and performance of +infrastructure components (i.e. servers and network devices), as well as +applications [ZABB]_. It can be customized for use with OpenStack. It is a +mature tool and has been proven to be able to scale to large systems with +100,000s of devices. + +Delay in execution of actions +_____________________________ + + +* Type: 'deficiency in performance' +* Description + + + To-be + + - After detecting a fault, the monitoring tool should immediately execute + the appropriate action, e.g. inform the manager through the NB I/F + + + As-is + + - A delay of around 10 seconds was measured in two independent testbed + deployments + + + Gap + + - Cause of the delay is a periodic evaluation and notification. Periodicity is configured + as 30s default value and can be reduced to 5s but not below. + https://github.com/zabbix/zabbix/blob/trunk/conf/zabbix_server.conf#L329 + + +.. + vim: set tabstop=4 expandtab textwidth=80: |