Node and Role

SAP HANA Node

SAP HANA nodes are logical units that constitute an SAP HANA system. An SAP HANA node contains the CPU, memory, and storage (such as log, data, shared, and backup volumes) resources with specified specifications, as shown in Figure 1.

Figure 1 SAP HANA node

SAP HANA Studio

SAP HANA Studio provides management, monitoring, and information modeling of the SAP HANA system. It can also function as a client and provides capabilities to access user data. The information that the SAP HANA Studio provides includes the system information (such as software version), alarm information (generated by Statistics Server), and statistics of key system resources.

NAT Server

Provides the capability to switch to the HANA ECS using SSH. It allows you to switch to an SAP HANA node from the NAT server using Secure Shell (SSH).

SFS

Scalable File Service (SFS) provides the file sharing service. Create a file system to provide the backup volumes and the shared path to SAP HANA nodes.

SAP HANA Roles

In SAP HANA cluster deployment mode, the roles assigned to SAP HANA nodes are shown in Figure 2.

Figure 2 Roles assigned to SAP HANA nodes

Each SAP HANA node has the NameServer and IndexServer processes. Table 1 provides the roles of the processes.

**Table 1** SAP HANA roles
Process	Type	Description
NameServer	Configured Role	Initially configured roles Master: functions as a global transaction coordinator, which coordinates global transactions and stores the global metadata of the information about the computing node cluster. A cluster has three master nodes configured, but only one of them is activated. Slave: An SAP HANA cluster can have one or more slave nodes configured in a distributed architecture to cache metadata and perform database operations assigned by the master node. A cluster has multiple slave nodes.
NameServer	Actual Role	Activated roles due to the election mechanism Master: activated master node elected from the configured master nodes Slave: nodes except master nodes
IndexServer	Configured Role	Initially configured roles Worker: nodes that are running and performing database operations Standby: takes over services of a faulty node. A cluster can have no or any number of standby nodes, and one standby node by default. In normal cases, software on the node is running, but the node's memory database has no data and cannot process services. The standby node takes over services of a faulty node automatically.
IndexServer	Actual Role	Activated roles due to the election mechanism Master: node elected from worker nodes. It is the same as the master node in Name Server. Slave: worker nodes except the master nodes Standby: same as parameter Config Role in Index Server. Any node can be the standby node due to multiple times of service switchovers.