Core Processes on an SAP HANA Single-Node Instance
Following the concept of a shared architecture, the name server, the index server of each tenant database, and the XS engine maintain data in the corresponding data and log volumes independently.
The following table gives you an overview of the most important server components of the SAP HANA database and the corresponding services:
|The name server, which runs in the system database only, owns the information about the topology of the SAP HANA system, including knowledge of the tenant databases that exist in the system. Information about the location of tables and table partitions is stored in the relevant tenant database catalog.
|The index server, which runs in every tenant database (but not the system database), contains the actual data stores and the engines for processing the data.
|The compile server performs the compilation of stored procedures and programs, for example, SQLScript procedures. It runs on every host and does not persist data. It runs in the system database and serves all tenant databases.
|The preprocessor server is used by the index server to analyze text data and extract the information on which the text search capabilities are based. It runs in the system database and serves all tenant databases.
|SAP Web Dispatcher
|The Web Dispatcher processes inbound HTTP and HTTPS connections to XS classic services.
|SAP start service
|The SAP start service is responsible for starting and stopping the other services in the correct order. It also performs other functions, such as monitoring their runtime state.
In addition to the core servers, the following optional servers may also be running:
|XS advanced runtime
SAP HANA includes a run-time environment for application development: SAP HANA extended application services, advanced model (XS advanced). The SAP HANA XS advanced model represents an evolution of the application server architecture within SAP HANA by building upon the strengths (and expanding the scope) of previous SAP HANA extended application services, classic model (XS classic).
The SAP HANA XS advanced runtime consists of several processes for platform services and for executing applications.
|XS classic server
SAP HANA extended application services, classic model (XS, classic) is the application server for native SAP HANA-based web applications. It is installed with the SAP HANA database and allows developers to write and run SAP HANA-based applications without the need to run an additional application server. SAP HANA XS is also used to run web-based tools that come with SAP HANA, for instance for administration, lifecycle management and development.
SAP HANA XS, classic and the SAP HANA repository are deprecated as of SAP HANA 2.0 SPS 02. For more information, see SAP Note 2465027.
|SAP HANA Deployment Infrastructure (HDI) server
|HDI handles the deployment of design-time artifacts into the SAP HANA database. If XS advanced is installed in the system, HDI is already enabled. Otherwise, you must enable it manually.
The Services card shows the status of the SAP HANA database system. The status can be, for example, running, running with issues, or stopped. Choosing the card brings you to Manage Services.
In the Manage Services application, you see the status of all the services in the database. For each service, detailed information about its memory consumption is available. You can also stop or kill a service. In the Manage Services app of the system database, you can also start or stop the complete SAP HANA database system.
The Reset Memory Statistics button (1) lets you clear the statistics history. This can be very useful when you need to focus on the most recent memory statistics to investigate a problem.
The Go to Alerts button (2) lets you directly open the Alerts application to investigate the alerts associated to this resource.
The Start Missing Services button (3) allows you to start any inactive services. Start Missing Services can only be performed in the Manage Services application of the system database.
The Kill Service button (4) stops the selected service immediately and if the related option is selected, creates a crash dump file. Normally the SAP HANA daemon will restart the killed service.
The Settings icon (5) lets you add and remove columns from the display. Not all columns are visible by default.
The CPU column (6) displays a mini chart visualizing the CPU usage of the service. Choosing the mini chart opens the Performance Monitor for a more detailed breakdown of CPU usage.
The Memory column (7) provides a mini chart visualizing the memory usage of the service. The different colors represent the following:
- Dark green shows the service's used memory.
- Light green shows the service's peak memory.
- The gray stroke represents the effective allocation limit.
- The light gray background represents the physical memory.
Choosing the mini chart opens the Memory Analysis app for a more detailed breakdown of memory usage.
The Status column (8) provides information on the status of the service. The following status values are possible:
- Running with Issues (where at least one service is not running, or there is at least one high alert)
- Not Running
To investigate why the service is not running, you can navigate to the crash dump file created when the service stopped.NoteAt operating system level, the crash dump file can be found in the databases trace directory. Here as an example for a tenant database:
The Service Alerts (9) column shows the number of alerts triggered by the service. A link to the Alert application that shows the alert with the highest priority is provided as well.