Updated at: 2022-12-09 03:49:50
► Entity:
In an AIOps scenario, an entity is an IT infrastructure component. An entity is usually a host, and may be any of the following components:
• Physical or virtual server
• Network device (switch, router)
• Storage system or volume
• Operating system process
• Software application (e.g. database, web server, business application)
• Application process instance (for example, 2 instances of the same web server application are 2 separate entities)
Key performance indicators (KPI) are used to return specific values for performance indicators such as, CPU load percentage, memory usage percentage, or response time. The aggregated values returned by the KPI are used to monitor the health of each service and locate trends with possible anomalies.
► Service
In an AIOps scenario, a service represents the service in real running environment, and can monitor the health of IT system and business process. Including: 
• An application or a group of applications
• An infrastructure layer (e.g. web, database, or network layer)
• A business service with multiple layers
• A single process
► Index
An index can be regarded as a collection of Elasticsearch storage logs. Index management is used to detect changes in Elasticsearch indexes regularly and synchronize the data to the log library. if the log library of the corresponding log type cannot be found during the index regular detection, the system will automatically create a new log library corresponding to the index log type.
► Log Library
Log library can be regarded as a collection of different types of indexes, through which the indexes can be managed by category, for warm data and hot data management. Besides, according to the log type, index creation rules and the number of shards configured in the log library, the system will automatically generate the corresponding indexes.