Starting and Stopping AS ABAP

The SAP MC also enables you to start and stop the database. This function is not implemented in other tools, such as the SAP Microsoft Management Console (SAP MMC) or SAPControl. With tools, such as SAPControl, the database is only started when a PAS or AAS instance is started on the same host on which the database is installed (on condition that the database belongs to the same SAP system).

On the host where the database of the SAP system is installed, an SAP Host Agent must be installed, too. The SAP Host Agent starts and stops the database and provides monitoring data from the operating system to the SAP MC. The SAP MC receives the core information from sapstartsrv of the SAP instances that communicates on which host the database is installed. The SAP MC connects to the SAP Host Agent of the communicated host via port 1128 (or 1129 for secure network communications - SNC).

The SAP MC holds a connection to each sapstartsrv process and the SAP Host Agent (see figure below).

When it comes to a start action, the SAP Host Agent is addressed first to start the database, if the status is Stopped. For all SAP instances the sapstartsrv negotiate, based on the priorityLEVEL, the further start sequence. Accordingly the instances are started. The communication takes place directly between the sapstartsrvdaemon or services. Instances with priorityLEVEL 1 (ASCS instance in ABAP environments) are in most scenarios started directly after the database, although they could also be started before the database. Central Services are not dependent on a successful connection to the database at this stage within the start procedure.

The procedure to start an ABAP-based SAP system with instance prioritiesLEVEL 1 and 3 is a typical scenario and explained here with the steps shown in the previous figure SAP MC: Sequence when Starting an SAP System (including Database) as follows:

1. The administrator uses the SAP MC to start the SAP system.

2. Before starting the SAP system, the SAP Host Agent on the database host receives the command to start the underlying database.

3. If the database has the status Stopped, the SAP Host Agent uses a database start command. In case the database status returns Running, the next step is executed.

4. The sapstartsrv of the instance with priorityLEVEL 1 receives the command to start the instances according to their priority. The connection point is the result of identifying the instance with the highest priorityLEVEL , which corresponds to the lowest number!

5. The instance with priorityLEVEL 1 is started by the corresponding sapstartsrv.

6. The sapstartsrv of the instance with priorityLEVEL 1 triggers the sapstartsrv of the instance with priorityLEVEL 3, signaling it to start its instance.

   Note

   In case there is a scaled SAP system given, which is a system with at least one further AAS instance, the signal to start will be sent in parallel to all instances with the same priorityLEVEL.

7. The instance with priorityLEVEL 3 is started by the respective sapstartsrv.

The status of a database in the SAP MC is self-explanatory, according to the colors (already discussed in a former lesson): a stopped database is displayed in gray, a started database in green color. In phases starting and stopping it shows up in yellow color.

You can start and stop the database independently from the SAP system in the SAP MC by expanding the Database node and selecting the relevant option in the context menu based on the <DBSID>.

In the Navigation Pane on the left of the SAP MC the SAP system displays directly or included in a Landscape (folder). The individual SAP systems can be expanded to view details, for example different types of SAP instances, and further down other elements like Process Lists, technical information, and monitoring data.

Different colors are used to identify the status of systems, instances, processes, and services within the SAP MC (please refer to the list in the predecessor lesson).

When an access to an SAP system in the Navigation Pane takes place for the first time after starting the SAP MC, an authentication box appears, requesting an operating system user and password. Typically the <sid>adm will be used. This user is authorized to start and stop an entire SAP system or individual instances. The SAP MC remembers the credentials until closing the tool.

In the context of starting a complete SAP system, there is an option to select which components should be started (see step no. 2 in figure above). The default settings is All Instances. The SAP MC starts the individual instances of the system according to the start priorityLEVEL and in the correct sequence. Nevertheless, alternatively the administrative personnel are able to choose another variant, like type of instance or priorityLEVEL.

A further option when starting an SAP system is the definition of so called start timeout. This can be seen in the figure above at step 2, looking at the dialog box. This start timeout is defined as a maximum period for the instance to start. If all instances with the same priorityLEVEL do not start within this timespan, instances with the next priorityLEVEL cannot be started. The default value is 300 seconds and can be overridden in the field of the dialog box. The timeout countdown begins again when the start process of another priorityLEVEL is completed. If the start timeout limit was reached, the remaining SAP instances are not started and the procedure will be stopped.

From a handling perspective the administrative personnel are supported by visualization features in the SAP MC. By selecting a specific node (for example, an instance) in the Navigation Pane tree structure at the left of the SAP MC, the details about the current status of the single elements can be identified. The information is provided in the Result Pane on the right.

Here are some example statuses during startup of an SAP system:

• Running

  All elements of the selected component have been started successful and are running.

• Running but status info unavailable

  All elements of the selected component have been started successful, but no further information is available.

• Server startup procedure running

  The start was initialized and the procedure is still ongoing, but did not yet finish.

• Dialog Queue standstill

  This status indicates that the start process is not fully finished and that ABAP work processes may not yet be fully initialized.

In any case use the recommended best practice procedure for verification of a start action, which is logging on to the system or instance to check the system availability.

When an SAP system is stopped using the SAP MC, the stop process is executed following the reverse sequence of the start process taking the priorityLEVEL into account. After calling the stop process, a dialog window appears where you can choose between hard and soft shutdown options. Soft shutdown means that no further user requests are received by the instance and processes are terminated if no process is handling a request. Hard shutdown means that all request processing is terminated immediately and open transactions are rolled back in the underlying database.

The Soft shutdown timeout specifies how much time instances with the same priorityLEVEL are given to complete the stop process before instances with the next lowest priorityLEVEL are stopped. If the PAS and AAS instances (with priority 3) cannot be stopped within 300 seconds, for example, the ASCS instance (with priorityLEVEL 1) is stopped once this timeout has expired, and so on.

The figure above clarifies the different statuses during an SAP system stop procedure. The statuses on the left show in which sequence the instances of the SAP system are stopped, whilst on the right the statuses of the processes of one AS instance can be seen. In this case it is the PAS instance of the SAP system.

As already discussed in this and a predecessor lesson, only some databases can profit from an integrated database shutdown within the SAP MC and if specific conditions are fulfilled. If it is supported in the specific scenario, the flag Include Database is active and can be set by the administrator when stopping the SAP system.

In some situations it is meaningful to start an SAP system stepwise or even start or restart only individual instances. The SAP MC provides the complete range of functionality and supports the administrative department with those features. The required options are provided in the Navigation Pane by making use of the context menu of the instance nodes.

A typical use case is an instance Restart. There are different reasons why an individual instance Restart might be necessary, for example:

• Parameter changes to activate new parameter values

• Solving hardware allocation problems (for example, main memory or CPU)

• Operating system software maintenance or parametrization with the need of a reboot

• Hardware changes

In highly scaled ABAP environments with multiple AAS instances, the administration might not start the SAP systems completely. Initially specific instances are started in the correct sequence and others remain offline, for example because of the need for a further downtime window.

The relevant start and stop handling options for individual instances can be found in the context menu of the respective instance in the Navigation Pane underneath the <SAPSID>. Depending on the current status of an instance, the functions Start... or Stop... are active or inactive (grayed out). The function Restart... always appears as an active option, as even if an instance is stopped, it simply gets started with this function (without a preceding stop action).

When you expand the instance, other elements are displayed in the SAP MC, such as the Process List and the AS ABAP WP Table. The Process List provides status information about the start process and indicates which processes and/or services have been started by the responsible sapstartsrv. At the beginning of the start process, it is possible to see the sapcpe process in the Process List, verifying, whether a replication of kernel binaries is needed.

In the figure, you can see that the ABAP Dispatcher (disp+work) of the AAS instance is still starting. The IGS Watchdog (igswd_mt), the RFC Gateway (gwrd) and the Internet Communication Manager (icman) are already running.

By checking the content of the AS ABAP WP Table, the status of a PAS or AAS instance can be verified. The status of the individual ABAP work processes, allows a conclusion of the overall status of an instance and in whether the initialization was completed (column Start displays yes).

Only as a reminder:

As already discussed in a former lesson, SAPControl is a command line tool for starting and stopping SAP systems. It uses the Web Service interface of the sapstartsrv, is part of the SAP kernel, and is available on all supported operating system platforms.

The following figure shows the basic structure of the syntax with some selected examples. The execution is not yet shown, but will follow in the flow of this lesson.

As you can see in the figure above, there are multiple alternatives to start or stop an SAP system or elements of it with SAPControl. Most methods use by default hard shutdown options. With further parameters it is possible to trigger a soft shutdown, which can be limited, so that after a time limit is reached, the stop continues with a hard shutdown.

In addition there is a Webmethod to handle the sapstartsrv. For example to restart the daemon or service after important changes, which affect the processes to be started by an instance.

In SAP environments there are different predefined OS users for the use case of start and stop actions. The main approach uses the <sid>adm created during installation. In addition an OS user with access to the SAP Host Agent is able to make use of SAPControl functions.

Which option should be used, highly depends on the environment (OS, user, security configuration, and so on) and is not discussed in details in this class. Nevertheless, there are some hints and use cases within this lesson.

Before starting or stopping an SAP system using SAPControl, check the status of the SAP instances building the SAP system (please refer to the previous lesson). Alternatively use a command on OS-level to check the status of the relevant processes (for example, ps -ef | grep or pstree).

In the first example sapcontrol -user <user> <password> -nr <instance_number> -function StartSystem ALL, the web method StartSystem is called with the option ALL. As with the SAP MC, a sapstartsrv process is addressed to start the instances. ALL means that all instances are started according to the given priorityLEVEL. It is assumed that the instances exist and are not already operational. Typically the ASCS with an assigned priorityLEVEL 1 will take over control.

The PAS and any AAS instances have priorityLEVEL 3 and are started after the ASCS instance is running. Instances can run on the same host or on different hosts. With StartSystem LEVEL 3, which corresponds to the above used and mentioned StartSystemALL, the complete SAP system is started according to the priority of the individual instances, unless the instances are already running. This is the same process as with a system start using SAP MC.

Another alternative is the use of a protected web method to use a trusted connection. No user name or password is provided because the operating system authentication as <sid>adm is sufficient. However, it is only possible to execute a protected web method for the local host.

• UNIX/Linux: sapcontrol -prot NI_HTTP -nr <instance_number> -function Start

• Windows: sapcontrol -prot PIPE -nr <instance_number> -function Start

If the command is used based on a specific instance like with WebmethodStart or Stop, it should work properly. But in case StartSystemALL or option LEVEL 3 is used, it will fail in a distributed environment with instances installed on different hosts. The communication with instances on other hosts is not permitted under trust connections. Only local functions can be executed with this method.

The limitation of executing protected web methods only on a local basis can be eliminated with the use of option -systempki. In this way it is possible to use Webmethods like StartSystempriorityLEVEL or StartSystemALL instead of explicitly specifying the OS user and password with the option -<user > <password> in the command line. This method also works in distributed environments, where the instances are installed on different hosts. Nevertheless, a dedicated configuration is needed to make use of this option (not covered in this class).

The following commands are examples using the option -systempki:

• sapcontrol -systempki <path_to_instance_profile><name_of_instance_profile> -nr <instance_number> -function StartSystem ALL

• sapcontrol -systempki <path_to_instance_profile><name_of_instance_profile> -nr <instance_number> -function StopSystem LEVEL 3

The Microsoft Management Console (SAP MMC) is used on Windows operating system platforms. The installation of an SAP system on Windows adds a Snap-in to make available SAP systems in the console, in order to provide start and stop functions. This tool, with the Snap-in, is called SAP MMC and can be used on any Windows operating system platform, so even on front-end computers. SAP systems on platform UNIX/Linux can be included using the Snap-in.

The SAP MMC is OS-dependent and provides functions comparable to the SAP MC.

When stopping or restarting an SAP system in the SAP MMC, options will be provided on how to shutdown. There is no difference in comparison to the already discussed tools SAP MC and SAPControl. The following figure shows the corresponding options.