# Parameter Reference
<a name="sap-hana-pacemaker-rhel-parameters"></a>

The cluster setup uses parameters, including SID and System Number that are unique to your setup. It is useful to predetermine the values with the following examples and guidance.

**Topics**
+ [Global AWS Parameters](#global_shared_aws_parameters)
+ [Amazon EC2 Instance Parameters](#_amazon_ec2_instance_parameters)
+ [SAP and Pacemaker Resource Parameters](#_sap_and_pacemaker_resource_parameters)
+ [Red Hat Cluster Parameters](#_red_hat_cluster_parameters)

## Global AWS Parameters
<a name="global_shared_aws_parameters"></a>


| Name | Parameter | Example | 
| --- | --- | --- | 
|  AWS account ID |  `<account_id>`  |  `123456789100`  | 
|  AWS Region |  `<region>`  |  `us-east-1`  | 
+  AWS account – For more details, see [Your AWS account ID and its alias](https://docs.aws.amazon.com/IAM/latest/UserGuide/console-account-alias.html).
+  AWS Region – For more details, see [Describe your Regions](https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/using-regions-availability-zones.html#concepts-availability-zones).

## Amazon EC2 Instance Parameters
<a name="_amazon_ec2_instance_parameters"></a>


| Name | Parameter | Primary example | Secondary example | 
| --- | --- | --- | --- | 
| Amazon EC2 instance ID |  `<instance_id_x>`  |  `i-xxxxinstidforhost1`  |  `i-xxxxinstidforhost2`  | 
| Hostname |  `<hostname_x>`  |  `hanahost01`  |  `hanahost02`  | 
| Host IP |  `<host_ip_x>`  |  `10.1.20.1`  |  `10.2.20.1`  | 
| Host additional IP |  `<host_additional_ip_x>`  |  `10.1.20.2`  |  `10.2.20.2`  | 
| Configured subnet |  `<subnet_id>`  |  `subnet-xxxxxxxxxxsubnet1`  |  `subnet-xxxxxxxxxxsubnet2`  | 
+ Hostnames must comply with SAP requirements outlined in [SAP Note 611361 - Hostnames of SAP ABAP Platform servers](https://me.sap.com/notes/611361) (requires SAP portal access).
+ Run the following command on your instances to retrieve the hostname:

  ```
  $ hostname
  ```
+ Amazon EC2 instance ID – run the following command (IMDSv2 compatible) on your instances to retrieve instance metadata:

  ```
  $ /usr/bin/curl --noproxy '*' -w "\n" -s -H "X-aws-ec2-metadata-token: $(curl --noproxy '*' -s -X PUT "http://169.254.169.254/latest/api/token" -H "X-aws-ec2-metadata-token-ttl-seconds: 21600")" http://169.254.169.254/latest/meta-data/instance-id
  ```

  For more details, see [Retrieve instance metadata](https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/instancedata-data-retrieval.html) and [Instance identity documents](https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/instance-identity-documents.html).

 **For Scale-out Deployments** 


| Role | Primary Coordinator | Primary Worker | Primary Worker | Secondary Coordinator | Secondary Worker | Secondary Worker | Majority Maker | 
| --- | --- | --- | --- | --- | --- | --- | --- | 
| Hostname |  `hanahost01`  |  `hanahostworker01a`  |  `hanahostworker01b`  |  `hanahost02`  |  `hanahostworker02a`  |  `hanahostworker02b`  |  `hanamm`  | 
| Subnet |  `subnet-xxxxxxxxxxsubnet1`  |  `subnet-xxxxxxxxxxsubnet1`  |  `subnet-xxxxxxxxxxsubnet1`  |  `subnet-xxxxxxxxxxsubnet2`  |  `subnet-xxxxxxxxxxsubnet2`  |  `subnet-xxxxxxxxxxsubnet2`  |  `subnet-xxxxxxxxxxsubnet3`  | 
+ Example for a 6 node cluster with a majority maker
+ The majority maker can use minimal resources as it only provides cluster quorum functionality

## SAP and Pacemaker Resource Parameters
<a name="_sap_and_pacemaker_resource_parameters"></a>


| Name | Parameter | Example | 
| --- | --- | --- | 
| SAP HANA SID |  `<SID>` or `<sid>`  |  `HDB`  | 
| SAP HANA System Number |  `<hana_sys_nr>`  |  `00`  | 
| SAP HANA Virtual Hostname |  `<hana_virt_hostname>`  |  `hanahdb`  | 
| SAP HANA Overlay IP |  `<hana_overlayip>`  |  `172.16.52.1`  | 
| SAP HANA Read Enabled Overlay IP (optional) |  `<readenabled_overlayip>`  |  `172.16.52.2`  | 
| VPC Route Tables |  `<routetable_id>`  |  `rtb-xxxxxroutetable1`  | 
+ SAP details – SAP parameters, including SID and instance number must follow the guidance and limitations of SAP and Software Provisioning Manager. Refer to [SAP Note 1979280 - Reserved SAP System Identifiers (SAPSID) with Software Provisioning Manager](https://me.sap.com/notes/1979280) for more details.
+ Post-installation, use the following command to find the details of the instances running on a host:

  ```
  $ sudo /usr/sap/hostctrl/exe/saphostctrl -function ListInstances
  ```
+ Overlay IP – This value is defined by you. For more information, see [Overlay IP](sap-hana-pacemaker-rhel-concepts.md#overlay-ip-rhel).

## Red Hat Cluster Parameters
<a name="_red_hat_cluster_parameters"></a>


| Name | Parameter | Example | 
| --- | --- | --- | 
| Cluster user |  `<cluster_user>`  |  `hacluster`  | 
| Cluster password |  `<cluster_password>`  |  | 
| Cluster name |  `<cluster_name>`  |  `myCluster`  | 
|  AWS CLI cluster profile |  `<cli_cluster_profile>`  |  `cluster`  | 
+ Cluster user – Installing cluster packages will create the user hacluster, set a password to this account to ensure that the cluster can perform the tasks which do not require root access.