SAP Host Agent.

SAP Host Agent is an agent (tool) that can accomplish several life-cycle management tasks, such as operating system monitoring, database monitoring, system instance control and provisioning in SAP.

SAP Host Agent is installed automatically during the installation of new SAP system instances with SAP kernel 7.20 or higher. Also  SAP Host Agent is upgraded automatically as part of the SAP system instance patching or upgrade the SAP kernel. However, you can also install and upgrade SAP Host Agent independently.

SAP strongly recommended that regularly upgrade SAP Host Agent to its latest version.

SAP Host Agent provides you with the following features:

• SAP instance discovery and inventory
• SAP instance control
• Database monitoring and management
• System or instance provisioning:  Hosting the infrastructure of SAP Landscape Virtualization Management (LVM)  & Hosting software lifecycle (SL) tools interfaces                                                          
• Operating system monitoring  :  Using saposcol  & Using Common Information Model (CIM) based infrastructures

The installed programs are started automatically when the host is booted

Windows - This is done by the services saphostcontrol and saphostexec

Unix - The automatic start is ensured by the startup script sapinit

Ø Important Services

saphostexec -  life-cycle management processes, using for  upgrade and installation. Runs under root user in Unix & Administrator user in Windows.

saphostacontrol - monitors hosts, runs under sapadm user

saposcol - saposcol is a stand-alone program that runs in the operating system background. It runs independently of SAP instances exactly once per monitored host. saposcol have following features,

• Usage of virtual and physical memory
• CPU utilization
• Utilization of physical disks and file systems
• Resource usage of running processes

Ø Executable 

UNIX   - /usr/sap/hostctrl/exe

Windows  -  %ProgramFiles%\SAP\hostctrl\exe

Ø Profile File

The profile parameters of SAP Host Agent are stored in the host_profile file. This file is located in the executable directory of the SAP Host Agent.

Ø Work Directory 

UNIX   - /usr/sap/hostctrl/work

Windows  -  %ProgramFiles%\SAP\hostctrl\work

Ø Log Files

The following log files are created during runtime for SAP Host Agent. They are available in the working directory.

sapstartsrv.log - Contains the developer trace for sapstartsrv

dev_saphostexec - Contains the developer trace for saphostexec

sapstartsrv_ccms.log - This log file is for central monitoring. It is stored in subdirectory sapccmsr of the working directory

dev_sapdbctrl- Contains the developer trace for sapdbctrl

Ø saphostexec commands 

saphostexec -help

Lists all command line options of saphostexec with documentation

saphostexec -status

Returns the status of SAP Host Agent

saphostexec -version

Returns the version of SAP Host Agent with detailed information

saphostexec -restart

Starts or restarts SAP Host Agent

saphostexec -stop

Stops a running SAP Host Agent

saphostexec -uninstall

Uninstalls SAP Host Agent

saphostexec -install

Installs SAP Host Agent

saphostexec -upgrade

Upgrades SAP Host Agent

Use the additional parameter -verify for Install & upgrade options  to verify the content of the installation package against the SAP digital signature

Also use -archive option while executing saphostexec from hostctrl directory of the existing SAP Host Agent installation, you use the -archive parameter to provide the direct path to the archive with the required target release version without manually extracting the archive before.