Distributed HA Deployment Mode

Figure 1 shows the distributed HA deployment mode of SAP NetWeaver.

In this deployment mode, the SAP NetWeaver system consists of multiple SAP instances. An SAP instance is a group of processes that are simultaneously started or stopped. In the distributed HA deployment mode, all instances are deployed on separated ECSs. The main instances are as follows:

• ASCS instance (ASCS instance)
• Enqueue Replication Server instance (ERS instance)
• Database instance (DB instance)
• Primary Application Server instance (PAS instance)
• Additional Application Server instance (AAS instance)

Table 1 lists the SAP NetWeaver component features.

Customers can install SAP NetWeaver as required and formulate deployment modes based on its component features to ensure HA. To avoid SPOF and ensure HA, the ASCS instance (including Message server and Enqueue server) requires the cloud platform and the database is configured with the cross-AZ active and standby switchover. Central instance and Dialog instance (including ABAP Dialog and Batch work process) can be installed on multiple ECSs to ensure HA.

Figure 2 shows the recommended distributed HA deployment mode of SAP NetWeaver on the public cloud.

The preceding describes an example of the SAP NetWeaver HA deployment mode. You can install SAP NetWeaver as required.

• ASCS instance (including Message server and Enqueue server) is a system that may have an SPOF. With the help of the cloud platform, ASCS instance is protected from an SPOF. Two ASCS ECSs need to be created and attached to a shared disk. The ASCS instance is installed on the active ECS, and the ERS instance is installed on the standby ECS. The time synchronization and disk formatting must be performed on the two ECSs.
• SAP HANA databases are deployed in the active/standby mode. The PAS instance is deployed on the active database and the AAS instance is deployed on the standby database. For details about how to install SAP HANA, see the SAP HANA User Guide.
• You can create an SFS Turbo file system to provide the file sharing storage. You can also use NFS to share files.
• The security group and elastic NICs are used to protect SAP NetWeaver Central instance, ASCS instance, and DB instance to avoid communication errors and isolate failed resources.
• Table 2 and Table 3 show the file system planning for the active and standby ASCS nodes.

  Table 2 File system planning for the active ASCS node

  Mount Point	File System Type	Description
  /usr/sap/<SID>/ASCS<##>	xfs NOTE: In the cross-AZ or cross-region scenario, this file system type is sfs.	Shared disk, which is used to install the ASCS instance. For details, see section Data Planning. NOTE: In the cross-AZ or cross-region deployment scenario, the SFS Turbo file system provides the shared storage.
  /sapmnt	sfs	SFS Turbo file system, which provides the shared storage. For details, see section Data Planning.
  /usr/sap/<SID>/SYS	sfs	SFS Turbo file system, which provides the shared storage. For details, see section Data Planning.
  /sapcd	sfs	SFS Turbo file system, which provides the shared storage. The SAP NetWeaver installation package is uploaded to this directory.

  Table 3 File system planning for the standby ASCS node

  Mount Point	File System Type	Description
  /usr/sap/<SID>/ERS<##>	xfs NOTE: In the cross-AZ or cross-region scenario, this file system type is sfs.	Shared disk, which is used to install the ERS instance. For details, see section Data Planning. NOTE: In the cross-AZ or cross-region deployment scenario, the SFS Turbo file system provides the shared storage.
  /sapmnt	sfs	SFS Turbo file system, which provides the shared storage. For details, see section Data Planning.
  /usr/sap/<SID>/SYS	sfs	SFS Turbo file system, which provides the shared storage. For details, see section Data Planning.
  /sapcd	sfs	SFS Turbo file system, which provides the shared storage. The SAP NetWeaver installation package is uploaded to this directory.

• Select a proper deployment mode as required. Table 4 lists the recommended application scenarios.