Terraform: HA cluster configuration guide for SAP NetWeaver on SLES

This guide shows you how to automate the deployment of a performance-optimized SUSE Linux Enterprise Server (SLES) high-availability (HA) cluster for SAP NetWeaver.

The guide uses Terraform to deploy two Compute Engine virtual machines (VMs), a virtual IP address (VIP) with an internal passthrough Network Load Balancer implementation, and an OS-based HA cluster, all according to the best practices from Google Cloud, SAP, and the OS vendor.

For information about deploying Compute Engine VMs for SAP NetWeaver that is not specific to high-availability, see the SAP NetWeaver deployment guide that is specific to your operating system.

To configure an HA cluster for SAP HANA on Red Hat Enterprise Linux (RHEL), see the HA cluster manual configuration guide for SAP NetWeaver on RHEL.

This guide is intended for advanced SAP NetWeaver users who are familiar with Linux high-availability configurations for SAP NetWeaver.

The system that this guide deploys

Following this guide, you will deploy two SAP NetWeaver instances and set up an HA cluster on SLES. You deploy each SAP NetWeaver instance on a Compute Engine VM in a different zone within the same region. A high-availability installation of the underlying database is not covered in this guide.

Overview of a high-availability Linux cluster for a single-node SAP NetWeaver system

The deployed cluster includes the following functions and features:

Two host VMs, one for the active ASCS instance and one for the active instance of the ENSA2 Enqueue Replicator or the ENSA1 Enqueue Replication Server (ENSA1). Both ENSA2 and ENSA1 instances are referred to as ERS.
The Pacemaker high-availability cluster resource manager.
A STONITH fencing mechanism.
Automatic restart of the failed instance as the new secondary instance.

Prerequisites

Before you create the SAP NetWeaver high availability cluster, make sure that the following prerequisites are met:

You have read the SAP NetWeaver planning guide and the High-availability planning guide for SAP NetWeaver on Google Cloud.
You or your organization has a Google Cloud account and you have created a project for the SAP NetWeaver deployment. For information about creating Google Cloud accounts and projects, see Creating a project in the SAP NetWeaver Deployment Guide for Linux.
If you require your SAP workload to run in compliance with data residency, access control, support personnel, or regulatory requirements, then you must create the required Assured Workloads folder. For more information, see Compliance and sovereign controls for SAP on Google Cloud.
If you are using VPC internal DNS, then the value of the vmDnsSetting variable in your project metadata must be either GlobalOnly or ZonalPreferred to enable the resolution of the node names across zones. The default setting of vmDnsSetting is ZonalOnly. For more information, see:
You have set up a file share using an NFS shared file storage solution, like Filestore Enterprise.
If OS login is enabled in your project metadata, you need to disable OS login temporarily until your deployment is complete. For deployment purposes, this procedure configures SSH keys in instance metadata. When OS login is enabled, metadata-based SSH key configurations are disabled, and this deployment fails. After deployment is complete, you can enable OS login again.

For more information, see:
- Enabling or disabling OS Login
- Add SSH keys to VMs that use metadata-based SSH keys

Related information from SUSE

Except where required for the Google Cloud environment, the information in this guide is consistent with the following related guides from SUSE:

Creating a network

For security purposes, create a new network. You can control who has access by adding firewall rules or by using another access control method.

If your project has a default VPC network, don't use it. Instead, create your own VPC network so that the only firewall rules in effect are those that you create explicitly.

During deployment, VM instances typically require access to the internet to download Google Cloud's Agent for SAP. If you are using one of the SAP-certified Linux images that are available from Google Cloud, the VM instance also requires access to the internet in order to register the license and to access OS vendor repositories. A configuration with a NAT gateway and with VM network tags supports this access, even if the target VMs do not have external IPs.

To create a VPC network for your project, complete the following steps:

Create a custom mode network. For more information, see Creating a custom mode network.
Create a subnetwork, and specify the region and IP range. For more information, see Adding subnets.

Setting up a NAT gateway

If you need to create one or more VMs without public IP addresses, you need to use network address translation (NAT) to enable the VMs to access the internet. Use Cloud NAT, a Google Cloud distributed, software-defined managed service that lets VMs send outbound packets to the internet and receive any corresponding established inbound response packets. Alternatively, you can set up a separate VM as a NAT gateway.

To create a Cloud NAT instance for your project, see Using Cloud NAT.

After you configure Cloud NAT for your project, your VM instances can securely access the internet without a public IP address.

Adding firewall rules

By default, incoming connections from outside your Google Cloud network are blocked. To allow incoming connections, set up a firewall rule for your VM. Firewall rules regulate only new incoming connections to a VM. After a connection is established with a VM, traffic is permitted in both directions over that connection.

You can create a firewall rule to allow access to specified ports, or to allow access between VMs on the same subnetwork.

Create firewall rules to allow access for such things as:

The default ports used by SAP NetWeaver, as documented in TCP/IP Ports of All SAP Products.
Connections from your computer or your corporate network environment to your Compute Engine VM instance. If you are unsure of what IP address to use, talk to your company's network admin.
Communication between VMs in a 3-tier, scaleout, or high-availability configuration. For example, if you are deploying a 3-tier system, you will have at least 2 VMs in your subnetwork: the VM for SAP NetWeaver, and another VM for the database server. To enable communication between the two VMs, you must create a firewall rule to allow traffic that originates from the subnetwork.
Cloud Load Balancing health checks.

To create the firewall rules for your project, see Creating firewall rules.

Creating a high-availability Linux cluster for SAP NetWeaver

The following instructions use a Terraform configuration file to create a SLES cluster with two SAP NetWeaver systems, a primary single-host SAP NetWeaver system on one VM instance and a standby SAP NetWeaver system on another VM instance in the same Compute Engine region.

You define configuration options for the SAP NetWeaver high-availability cluster in a Terraform configuration file.

Open the Cloud Shell.

Go to the Cloud Shell
Download the sap_nw_ha.tf configuration file for the SAP NetWeaver high-availability cluster to your working directory:
```
$ wget https://storage.googleapis.com/cloudsapdeploy/terraform/latest/terraform/sap_nw_ha/terraform/sap_nw_ha.tf
```
Note: Ensure that you have only a single Terraform configuration file in your working directory.
Open the sap_nw_ha.tf file in the Cloud Shell code editor.

To open the Cloud Shell code editor, click the pencil icon in the upper right corner of the Cloud Shell terminal window.

In the sap_nw_ha.tf file, update the argument values by replacing the contents inside the double quotation marks with the values for your installation. The arguments are described in the following table.

Argument	Data type	Description
`source`	String	Specifies the location and version of the Terraform module to use during deployment. The `sap_nw_ha.tf` configuration file includes two instances of the `source` argument: one that is active and one that is included as a comment. The `source` argument that is active by default specifies `latest` as the module version. The second instance of the `source` argument, which by default is deactivated by a leading `#` character, specifies a timestamp that identifies a module version. If you need all of your deployments to use the same module version, then remove the leading `#` character from the `source` argument that specifies the version timestamp and add it to the `source` argument that specifies `latest`.
`project_id`	String	Specify the ID of your Google Cloud project in which you are deploying this system. For example, `my-project-x`.
`machine_type`	String	Specify the type of Compute Engine virtual machine (VM) on which you need to run your SAP system. If you need a custom VM type, then specify a predefined VM type with a number of vCPUs that is closest to the number you need while still being larger. After deployment is complete, modify the number of vCPUs and the amount of memory. For example, `n1-highmem-32`.
`network`	String	Specify the name of the network in which you need to create the load balancer that manages the VIP. If you are using a shared VPC network, you must add the ID of the host project as a parent directory of the network name. For example, `HOST_PROJECT_ID/NETWORK_NAME`.
`subnetwork`	String	Specify the name of the subnetwork that you created in a previous step. If you are deploying to a shared VPC, then specify this value as `SHARED_VPC_PROJECT_ID/SUBNETWORK`. For example, `myproject/network1`.
`linux_image`	String	Specify the name of the Linux operating system image on which you want to deploy your SAP system. For example, `sles-15-sp5-sap`. For the list of available operating system images, see the Images page in the Google Cloud console.
`linux_image_project`	String	Specify the Google Cloud project that contains the image that you have specified for the argument `linux_image`. This project might be your own project or a Google Cloud image project. For a Compute Engine image, specify `suse-sap-cloud`. To find the image project for your operating system, see Operating system details.
`sap_primary_instance`	String	Specify a name for the VM instance for the primary SAP NetWeaver system. This is your initial ASCS location. The name can contain lowercase letters, numbers, or hyphens and must not exceed 13 characters.
`sap_primary_zone`	String	Specify a zone in which the primary SAP NetWeaver system is deployed. The primary and secondary zones must be in the same region. For example, `us-east1-b`.
`sap_secondary_instance`	String	Specify a name for the VM instance for the secondary SAP NetWeaver system. This is your initial ERS location. The name can contain lowercase letters, numbers, or hyphens and must not exceed 13 characters.
`sap_secondary_zone`	String	Specify a zone in which the secondary SAP NetWeaver system is deployed. The primary and secondary zones must be in the same region. For example, `us-east1-c`.
`nfs_path`	String	Specify the NFS mount point for the shared file system. For example, `10.163.58.114:/ssd_nfs`. Note: The NFS mount point for the shared file system must be empty before you apply the Terraform configuration.
`sap_sid`	String	Specify an SAP system ID. The ID must consist of three alpha-numeric characters and begin with a letter. All letters must be in uppercase. For example, `ED1`.
`hc_firewall_rule_name`	String	Optional. Specify a name for the health check firewall rule. The default value is `SAP_SID-hc-allow`.
`hc_network_tag`	String	Optional. Specify one or more comma-separated network tags that you want to associate with your VM instances for the health check firewall rule. The default value is `SAP_SID-hc-allow-tag`.
`scs_inst_group_name`	String	Optional. Specify a name for the ASCS instance group. The default value is `SAP_SID-scs-ig`.
`scs_hc_name`	String	Optional. Specify a name for the ASCS health check. The default value is `SAP_SID-scs-hc`.
`scs_hc_port`	String	Optional. Specify a port for the ASCS health check. To avoid clashing with other services, designate the port number for the ASCS health check in the private range, 49152-65535. The default value is `60000`.
`scs_vip_address`	String	Optional. Specify an unused IP address within the subnetwork specified on `subnetwork` earlier to use as the virtual IP address for the ASCS instance. If nothing is specified, the deployment scripts automatically select an unused IP address from the specified subnetwork.
`scs_vip_name`	String	Optional. Specify a name for the ASCS virtual IP. The default value is `SAP_SID-scs-vip`.
`scs_backend_svc_name`	String	Optional. Specify a name for the ASCS backend service. The default value is `SAP_SID-scs-backend-svc`.
`scs_forw_rule_name`	String	Optional. Specify a name for the ASCS forwarding rule. The default value is `SAP_SID-scs-fwd-rule`.
`ers_inst_group_name`	String	Optional. Specify a name for the ERS instance group. The default value is `SAP_SID-ers-ig`.
`ers_hc_name`	String	Optional. Specify a name for the ERS health check. The default value is `SAP_SID-ers-hc`.
`ers_hc_port`	String	Optional. Specify a port for the ERS health check. To avoid clashing with other services, designate the port number for ERS health check in the private range, 49152-65535. The default value is `60010`.
`ers_vip_address`	String	Optional. Specify an unused IP address within the subnetwork specified on `subnetwork` earlier to use as the virtual IP address for the ERS instance. If nothing is specified, the deployment scripts automatically select an unused IP address from the specified subnetwork.
`ers_vip_name`	String	Optional. Specify a name for the ERS virtual IP. The default value is `SAP_SID-ers-vip`.
`ers_backend_svc_name`	String	Optional. Specify a name for the ERS backend service. The default value is `SAP_SID-ers-backend-svc`.
`ers_forw_rule_name`	String	Optional. Specify a name for the ERS forwarding rule. The default value is `SAP_SID-ers-fwd-rule`.
`usr_sap_size`	Integer	Optional. Specify the size of the `/usr/sap` disk in GB. The minimum size is 8 GB. The default value is `8`.
`sap_mnt_size`	Integer	Optional. Specify the size of the `/sapmnt` disk in GB. The minimum size is 8 GB. The default value is `8`.
`swap_size`	Integer	Optional. Specify the size of the swap volume in GB. The minimum size is 8 GB. The default value is `8`.
`sap_scs_instance_number`	String	Optional. Specify the ASCS instance number. The `sap_scs_instance_number` must be a two-digit number. If you need to specify a single digit number, then add a `0` in front of the number. For example, `07`. The default value is `00`.
`sap_ers_instance_number`	String	Optional. Specify the ERS instance number. The `sap_ers_instance_number` must be a two-digit number. If you need to specify a single digit number, then add a `0` in front of the number. For example, `07`. The default value is `10`.
`sap_nw_abap`	Boolean	Optional. Specify whether you are deploying an ABAP stack or a Java stack of SAP NetWeaver. For a Java stack of SAP NetWeaver, specify `false`. The default value is `true`.
`pacemaker_cluster_name`	String	Optional. Specify a name for the pacemaker cluster. The default value is `SAP_SID-cluster`.
`public_ip`	Boolean	Optional. To create an ephemeral public IP address for the VM instances, set the `public_ip` to `true`. The default value is `false`. Caution: When the `public_ip` is `false`, ensure that you have a NAT gateway configured with a network tag defined for the VM or you have provided the VM with another route to the internet. If there is no route to the internet, the installation fails.
`service_account`	String	Optional. Specify the email address of a user-managed service account to be used by the host VMs and by the programs that run on the host VMs. For example, `svc-acct-name@project-id.iam.gserviceaccount.com`. If you specify this argument without a value, or omit it, then the installation script uses the Compute Engine default service account. For more information, see Identity and access management for SAP programs on Google Cloud.
`network_tags`	String	Optional. Specify one or more comma-separated network tags that you want to associate with your VM instances for firewall or routing purposes. A network tag for the ILB components is automatically added to VM's Network tags. If `public_ip = false` and you do not specify a network tag, then make sure to provide another means of access to the internet.
`sap_deployment_debug`	Boolean	Optional. Only when Cloud Customer Care asks you to enable debugging for your deployment, specify `true`, which makes the deployment generate verbose deployment logs. The default value is `false`.
`primary_reservation_name`	String	Optional. To use a specific Compute Engine VM reservation for provisioning the VM instance that hosts your HA cluster's primary SAP HANA instance, specify the name of the reservation. By default, the installation script selects any available Compute Engine reservation based on the following conditions. For a reservation to be usable, regardless of whether you specify a name or the installation script selects it automatically, the reservation must be set with the following: The `specificReservationRequired` option is set to `true` or, in the Google Cloud console, the Select specific reservation option is selected. Some Compute Engine machine types support CPU platforms that are not covered by the SAP certification of the machine type. If the target reservation is for any of the following machine types, then the reservation must specify the minimum CPU platforms as indicated: `n1-highmem-32`: Intel Broadwell `n1-highmem-64`: Intel Broadwell `n1-highmem-96`: Intel Skylake `m1-megamem-96`: Intel Skylake The minimum CPU platforms for all of the other machine types that are certified by SAP for use on Google Cloud conform to the SAP minimum CPU requirement.
`secondary_reservation_name`	String	Optional. To use a specific Compute Engine VM reservation for provisioning the VM instance that hosts your HA cluster's secondary SAP HANA instance, specify the name of the reservation. By default, the installation script selects any available Compute Engine reservation based on the following conditions. For a reservation to be usable, regardless of whether you specify a name or the installation script selects it automatically, the reservation must be set with the following: The `specificReservationRequired` option is set to `true` or, in the Google Cloud console, the Select specific reservation option is selected. Some Compute Engine machine types support CPU platforms that are not covered by the SAP certification of the machine type. If the target reservation is for any of the following machine types, then the reservation must specify the minimum CPU platforms as indicated: `n1-highmem-32`: Intel Broadwell `n1-highmem-64`: Intel Broadwell `n1-highmem-96`: Intel Skylake `m1-megamem-96`: Intel Skylake The minimum CPU platforms for all of the other machine types that are certified by SAP for use on Google Cloud conform to the SAP minimum CPU requirement.

The following example shows a completed configuration file that defines a high-availability cluster for SAP NetWeaver. The cluster uses an internal passthrough Network Load Balancer to manage the VIP.

Terraform deploys the Google Cloud resources that are defined in the configuration file and then scripts take over to configure the operating system and configure the Linux HA cluster.

For clarity, comments in the configuration file are omitted in the example.

   # ...
     module "sap_nw_ha" {
     source = "https://storage.googleapis.com/cloudsapdeploy/terraform/latest/terraform/sap_nw_ha/sap_nw_ha_module.zip"
   #
   # By default, this source file uses the latest release of the terraform module
   # for SAP on Google Cloud.  To fix your deployments to a specific release
   # of the module, comment out the source argument above and uncomment the source argument below.
   #
   # source = "https://storage.googleapis.com/cloudsapdeploy/terraform/202201240926/terraform/sap_nw_ha/sap_nw_ha_module.zip"
   #
   # ...
   #
   project_id = "example-project-123456"
   machine_type = "n2-highmem-32"
   network = "example-network"
   subnetwork = "example-subnet-us-central1"
   linux_image = "sles-15-sp3-sap"
   linux_image_project = "suse-sap-cloud"

   sap_primary_instance = "example-nw1"
   sap_primary_zone = "us-central1-a"

   sap_secondary_instance = "example-nw2"
   sap_secondary_zone = "us-central1-c"

   nfs_path = "10.223.55.130:/pr1_nw"

   sap_sid = "PR1"
   # ...
}

Initialize your current working directory and download the Terraform provider plugin and module files for Google Cloud:
```
terraform init
```
The terraform init command prepares your working directory for other Terraform commands.

To force a refresh of the provider plugin and configuration files in your working directory, specify the --upgrade flag. If the --upgrade flag is omitted and you don't make any changes in your working directory, Terraform uses the locally cached copies, even if latest is specified in the source URL.
```
terraform init --upgrade 
```
Optionally, create the Terraform execution plan:
```
terraform plan
```
The terraform plan command shows the changes that are required by your current configuration. If you skip this step, the terraform apply command automatically creates a new plan and prompts you to approve it.
Apply the execution plan:
```
terraform apply
```
When you are prompted to approve the actions, enter yes.

The terraform apply command sets up the Google Cloud infrastructure and then hands control over to a script that configures the HA cluster according to the arguments defined in the terraform configuration file.

While Terraform has control, status messages are written to the Cloud Shell. After the scripts are invoked, status messages are written to Logging and are viewable in the Google Cloud console, as described in Check the Logging logs.

Time to completion can vary, but the entire process usually takes less than 30 minutes.

Verifying the deployment of your SAP NetWeaver HA system

Verifying an SAP NetWeaver HA cluster involves several different procedures:

Check the logs
Check the configuration of the VM

Check the logs

In the Google Cloud console, open Cloud Logging to monitor installation progress and check for errors.

Note: You might incur costs when completing this step in Cloud Logging. For more information, see Cloud Logging pricing.

Go to Cloud Logging
Filter the logs:
Logs Explorer
1. In the Logs Explorer page, go to the Query pane.
2. From the Resource drop-down menu, select Global, and then click Add.
  
  If you don't see the Global option, then in the query editor, enter the following query:
```
resource.type="global"
"Deployment"
```
3. Click Run query.
Legacy Logs Viewer
- In the Legacy Logs Viewer page, from the basic selector menu, select Global as your logging resource.
Analyze the filtered logs:
- If "--- Finished" is displayed, then the deployment processing is complete and you can proceed to the next step.
- If you see a quota error:
  1. On the IAM & Admin Quotas page, increase any of your quotas that do not meet the SAP NetWeaver requirements that are listed in the SAP NetWeaver planning guide.
  2. Open Cloud Shell.
    
    Go to Cloud Shell
  3. Go to your working directory and delete the deployment to clean up the VMs and persistent disks from the failed installation:
```
terraform destroy
```
    When you are prompted to approve the action, enter yes.
  4. Rerun your deployment.

Check the configuration of the VM

After the VM instances deploy without errors, connect to each VM by using SSH. From the Compute Engine VM instances page, you can click the SSH button for each VM instance, or you can use your preferred SSH method.
Change to the root user.
```
sudo su -
```

At the command prompt, enter df -h. Ensure that you see output that includes the /usr/sap directories, such as /usr/sap/trans.

example-nw1:~ # df -h
  Filesystem                             Size  Used Avail Use% Mounted on
  ...
  /dev/mapper/vg_usrsap-vol              8.0G   41M  8.0G   1% /usr/sap
  /dev/mapper/vg_sapmnt-vol              8.0G   41M  8.0G   1% /sapmnt
  10.233.55.130:/pr1_nw/sapmntPR1       1007G     0  956G   0% /sapmnt/PR1
  10.223.55.130:/pr1_nw/usrsaptrans     1007G     0  956G   0% /usr/sap/trans
  10.223.55.130:/pr1_nw/usrsapPR1ASCS00 1007G     0  956G   0% /usr/sap/PR1/ASCS00
  ...

autofs is automatically configured during the deployment to mount the common shared file directories when the file directories are first accessed. The mounting of the ASCSASCS_INSTANCE_NUMBER and ERSERS_INSTANCE_NUMBER directories is managed by the cluster software, which is also set up during deployment.

Check the status of the new cluster by entering the status command: crm status

You should see results similar to the following the example, in which both VM instances are started and example-nw1 is the active primary instance:

example-nw1:~ # crm status
Cluster Summary:
  * Stack: corosync
  * Current DC: example-nw1 (version 2.0.4+20200616.2deceaa3a-3.6.1-2.0.4+20200616.2deceaa3a) - partition with quorum
  * Last updated: Fri Jun 18 05:47:48 2021
  * Last change:  Fri Jun 18 05:41:32 2021 by root via cibadmin on example-nw1
  * 2 nodes configured
  * 8 resource instances configured
Node List:
  * Online: [ example-nw1 example-nw2 ]
Full List of Resources:
  * fence-PR1-example-nw1     (stonith:fence_gce):           Started example-nw2
  * fence-PR1-example-nw2     (stonith:fence_gce):           Started example-nw1
  * file-system-PR1-ASCS00    (ocf::heartbeat:Filesystem):      Started example-nw1
  * file-system-PR1-ERS10     (ocf::heartbeat:Filesystem):      Started example-nw2
  * health-check-PR1-ASCS00   (ocf::heartbeat:anything):        Started example-nw1
  * health-check-PR1-ERS10    (ocf::heartbeat:anything):        Started example-nw2
  * vip-PR1-ASCS00      (ocf::heartbeat:IPaddr2):             Started example-nw1
  * vip-PR1-ERS10       (ocf::heartbeat:IPaddr2):             Started example-nw2

Test the ASCS and ERS load balancer setup by using the socat utility:

On each VM instance, temporarily start a socat process that returns its own hostname:

socat TCP-LISTEN:80,bind=0.0.0.0,fork,reuseaddr,crlf SYSTEM:"echo HTTP/1.0 200; echo Content-Type\: text/plain; echo; echo $(hostname)" &

On each node, use curl and try reaching the following IP addresses and hostnames. The IP addresses and hostnames can be found in /etc/hosts.
- 127.0.0.1
- localhost
- ASCS_VIRTUAL_HOST_NAME
- ASCS_IP_ADDRESS
- ERS_VIRTUAL_HOST_NAME
- ERS_IP_ADDRESS
- SCS VIP name, which is specified for the parameter scs_vip_name
- SCS VIP IP address, which is specified for the parameter scs_vip_address
- ERS VIP name, which is specified for the parameter ers_vip_name
- ERS VIP IP address, which is specified for the parameter ers_vip_address

The following is an example output from such a test:

example-nw1:~ # cat /etc/hosts
...
10.128.1.182 example-nw1.c.myproject.internal example-nw1
10.128.1.169 example-nw2.c.myproject.internal example-nw2
10.128.1.46 pr1-scs-vip.c.myproject.internal pr1-scs-vip
10.128.0.75 pr1-ers-vip.c.myproject.internal pr1-ers-vip
example-nw1:~ # curl 127.0.0.1
example-nw1
example-nw1:~ # curl localhost
example-nw1
example-nw1:~ # curl example-nw1
example-nw1
example-nw1:~ # curl 10.128.1.182
example-nw1
example-nw1:~ # curl example-nw2
example-nw2
example-nw1:~ # curl 10.128.1.169
example-nw2
example-nw1:~ # curl pr1-scs-vip
example-nw1
example-nw1:~ # curl 10.128.1.46
example-nw1
example-nw1:~ # curl pr1-ers-vip
example-nw2
example-nw1:~ # curl 10.128.0.75
example-nw2

If any of the validation steps show that the installation failed:

Resolve the errors.
Open Cloud Shell.

Go to Cloud Shell
Go to the directory that contains the Terraform configuration file.
Delete the deployment:
```
terraform destroy
```
When you are prompted to approve the action, enter yes.
Rerun your deployment.

Validate your installation of Google Cloud's Agent for SAP

After you have deployed a VM and installed your SAP system, validate that Google Cloud's Agent for SAP is functioning properly.

Verify that Google Cloud's Agent for SAP is running

To verify that the agent is running, follow these steps:

Establish an SSH connection with your host VM instance.

Run the following command:

systemctl status google-cloud-sap-agent

If the agent is functioning properly, then the output contains active (running). For example:

google-cloud-sap-agent.service - Google Cloud Agent for SAP
Loaded: loaded (/usr/lib/systemd/system/google-cloud-sap-agent.service; enabled; vendor preset: disabled)
Active:  active (running)  since Fri 2022-12-02 07:21:42 UTC; 4 days ago
Main PID: 1337673 (google-cloud-sa)
Tasks: 9 (limit: 100427)
Memory: 22.4 M (max: 1.0G limit: 1.0G)
CGroup: /system.slice/google-cloud-sap-agent.service
       └─1337673 /usr/bin/google-cloud-sap-agent

If the agent isn't running, then restart the agent.

Verify that SAP Host Agent is receiving metrics

To verify that the infrastructure metrics are collected by Google Cloud's Agent for SAP and sent correctly to the SAP Host Agent, follow these steps:

In your SAP system, enter transaction ST06.
In the overview pane, check the availability and content of the following fields for the correct end-to-end setup of the SAP and Google monitoring infrastructure:
- Cloud Provider: Google Cloud Platform
- Enhanced Monitoring Access: TRUE
- Enhanced Monitoring Details: ACTIVE

Install ASCS and ERS

The following section covers only the requirements and recommendations that are specific to installing SAP NetWeaver on Google Cloud.

For complete installation instructions, see the SAP NetWeaver documentation.

Prepare for installation

To ensure consistency across the cluster and simplify installation, before you install the SAP NetWeaver ASCS and ERS components, define the users, groups, and permissions and put the secondary server in standby mode.

Take the cluster out of maintenance mode:

# crm configure property maintenance-mode="false"

On both servers as root, enter the following commands, specifying the user and group IDs that are appropriate for your environment:
```
# groupadd -g GID_SAPINST sapinst
# groupadd -g GID_SAPSYS sapsys
# useradd -u UID_SIDADM SID_LCadm -g sapsys
# usermod -a -G sapinst SID_LCadm
# useradd -u UID_SAPADM sapadm -g sapinst

# chown SID_LCadm:sapsys /usr/sap/SID/SYS
# chown SID_LCadm:sapsys /sapmnt/SID -R
# chown SID_LCadm:sapsys /usr/sap/trans -R
# chown SID_LCadm:sapsys /usr/sap/SID/SYS -R
# chown SID_LCadm:sapsys /usr/sap/SID -R
```
Replace the following:
- GID_SAPINST: specify the Linux group ID for the SAP provisioning tool.
- GID_SAPSYS: specify the Linux group ID for the SAPSYS user.
- UID_SIDADM: specify the Linux user ID for the administrator of the SAP system (SID).
- SID_LC: specify the system ID (SID). Use lowercase for any letters.
- UID_SAPADM: specify the user ID for the SAP Host Agent.
- SID: specify the system ID (SID). Use uppercase for any letters.
For example, the following shows a practical GID and UID numbering scheme:
```
Group sapinst      1001
Group sapsys       1002
Group dbhshm       1003

User  en2adm       2001
User  sapadm       2002
User  dbhadm       2003
```

Install the ASCS component

On the secondary server, enter the following command to put the secondary server in standby mode:
```
# crm_standby -v on -N ${HOSTNAME};
```
Putting the secondary server in standby mode consolidates all of the cluster resources on the primary server, which simplifies installation.

Confirm that the secondary server is in standby mode:

# crm status

You should see output similar to the following example:

Stack: corosync
 Current DC: nw-ha-vm-1 (version 1.1.24+20201209.8f22be2ae-3.12.1-1.1.24+20201209.8f22be2ae) - partition with quorum
 Last updated: Thu May 27 17:45:16 2021
 Last change: Thu May 27 17:45:09 2021 by root via crm_attribute on nw-ha-vm-2

 2 nodes configured
 8 resource instances configured

 Node nw-ha-vm-2: standby
 Online: [ nw-ha-vm-1 ]

 Full list of resources:

  fencing-rsc-nw-aha-vm-1        (stonith:fence_gce):    Stopped
  fencing-rsc-nw-aha-vm-2        (stonith:fence_gce):    Started nw-ha-vm-1
  filesystem-rsc-nw-aha-scs      (ocf::heartbeat:Filesystem):    Started nw-ha-vm-1
  filesystem-rsc-nw-aha-ers      (ocf::heartbeat:Filesystem):    Started nw-ha-vm-1
  health-check-rsc-nw-ha-scs     (ocf::heartbeat:anything):      Started nw-ha-vm-1
  health-check-rsc-nw-ha-ers     (ocf::heartbeat:anything):      Started nw-ha-vm-1
  vip-rsc-nw-aha-scs     (ocf::heartbeat:IPaddr2):       Started nw-ha-vm-1
  vip-rsc-nw-aha-ers     (ocf::heartbeat:IPaddr2):       Started nw-ha-vm-1

On the primary server as the root user, change your directory to a temporary installation directory, such as /tmp, to install the ASCS instance by running the SAP Software Provisioning Manager (SWPM).
- To access the web interface of SWPM, you need the password for the root user. If your IT policy does not allow the SAP administrator to have access to the root password, you can use the SAPINST_REMOTE_ACCESS_USER.
- When you start SWPM, use the SAPINST_USE_HOSTNAME parameter to specify the virtual host name that you defined for the ASCS VIP address in the /etc/hosts file.
  
  For example:
```
cd /tmp; /mnt/nfs/install/SWPM/sapinst SAPINST_USE_HOSTNAME=vh-aha-scs
```
- On the final SWPM confirmation page, ensure that the virtual host name is correct.
After the configuration completes, take the secondary VM out of standby mode:
```
# crm_standby -v off -N ${HOSTNAME}; # On SECONDARY
```

Install the ERS component

On the primary server as root or SID_LCadm, stop the ASCS service.

# su - SID_LCadm -c "sapcontrol -nr ASCS_INSTANCE_NUMBER -function Stop"
# su - SID_LCadm -c "sapcontrol -nr ASCS_INSTANCE_NUMBER -function StopService"

On the primary server, enter the following command to put the primary server in standby mode:
```
# crm_standby -v on -N ${HOSTNAME};
```
Putting the primary server in standby mode consolidates all of the cluster resources on the secondary server, which simplifies installation.
Confirm that the primary server is in standby mode:
```
# crm status
```
On the secondary server as the root user, change your directory to a temporary installation directory, such as /tmp, to install the ERS instance by running the SAP Software Provisioning Manager (SWPM).
- Use the same user and password to access SWPM that you used when you installed the ASCS component.
- When you start SWPM, use the SAPINST_USE_HOSTNAME parameter to specify the virtual host name that you defined for the ERS VIP address in the /etc/hosts file.
  
  For example:
```
cd /tmp; /mnt/nfs/install/SWPM/sapinst SAPINST_USE_HOSTNAME=vh-aha-ers
```
- On the final SWPM confirmation page, ensure that the virtual host name is correct.
Take the primary VM out of standby to have both active:
```
# crm_standby -v off -N ${HOSTNAME};
```

Configure the SAP services

You need to confirm that the services are configured correctly, check the settings in the ASCS and ERS profiles, and add the SID_LCadm user to the haclient user group.

Confirm the SAP service entries

On both servers, confirm that your /usr/sap/sapservices file contains entries for both the ASCS and ERS services. To do this, you can use the systemV or systemd integration.

You can add any missing entries by using the sapstartsrv command with the pf=PROFILE_OF_THE_SAP_INSTANCE and -reg options.

For more information about these integrations, see the following SAP Notes:
- 3139184 - Linux: systemd integration for sapstartsrv and SAP Host Agent
- 3115048 - sapstartsrv with native Linux systemd support
systemV
The following is an example of how the entries for the ASCS and ERS services in the /usr/sap/sapservices file when you're using the systemV integration:
```
# LD_LIBRARY_PATH=/usr/sap/hostctrl/exe:$LD_LIBRARY_PATH; export LD_LIBRARY_PATH
/usr/sap/hostctrl/exe/sapstartsrv \
pf=/usr/sap/SID/SYS/profile/SID_ERSERS_INSTANCE_NUMBER_ERS_VIRTUAL_HOST_NAME \
-D -u SID_LCadm
/usr/sap/hostctrl/exe/sapstartsrv \
pf=/usr/sap/SID/SYS/profile/SID_ASCSASCS_INSTANCE_NUMBER_ASCS_VIRTUAL_HOST_NAME \
-D -u SID_LCadm
```
systemd
1. Verify that your /usr/sap/sapservices file contains entries for the ASCS and ERS services. The following is an example of how these entries appear in the /usr/sap/sapservices file when you're using the systemd integration:
```
systemctl --no-ask-password start SAPSID_ASCS_INSTANCE_NUMBER # sapstartsrv pf=/usr/sap/SID/SYS/profile/SID_ASCSASCS_INSTANCE_NUMBER_SID_LCascs
systemctl --no-ask-password start SAPSID_ERS_INSTANCE_NUMBER # sapstartsrv pf=/usr/sap/SID/SYS/profile/SID_ERSERS_INSTANCE_NUMBER_SID_LCers
```
2. Disable the systemd integration on the ASCS and the ERS instances:
  
  Caution: Disabling the systemd integration also stops the SAP instances.
```
# systemctl disable SAPSID_ASCS_INSTANCE_NUMBER.service
# systemctl stop SAPSID_ASCS_INSTANCE_NUMBER.service
# systemctl disable SAPSID_ERS_INSTANCE_NUMBER.service
# systemctl stop SAPSID_ERS_INSTANCE_NUMBER.service
```
3. Verify that the systemd integration is disabled:
```
# systemctl list-unit-files | grep sap
```
  An output similar to the following example means that the systemd integration is disabled. Note that some services, such as saphostagent and saptune, are enabled, and some services are disabled.
```
SAPSID_ASCS_INSTANCE_NUMBER.service disabled
SAPSID_ERS_INSTANCE_NUMBER.service disabled
saphostagent.service enabled
sapinit.service generated
saprouter.service disabled
saptune.service enabled
```
  For more information, see the SUSE document Disabling systemd services of the ASCS and the ERS SAP instances.

Stop the SAP services

On the secondary server, stop the ERS service:

# su - SID_LCadm -c "sapcontrol -nr ERS_INSTANCE_NUMBER -function Stop"
# su - SID_LCadm -c "sapcontrol -nr ERS_INSTANCE_NUMBER -function StopService"

On each server, validate that all services are stopped:

# su - SID_LCadm -c "sapcontrol -nr ASCS_INSTANCE_NUMBER -function GetSystemInstanceList"
# su - SID_LCadm -c "sapcontrol -nr ERS_INSTANCE_NUMBER -function GetSystemInstanceList"

You should see output similar to the following example:

GetSystemInstanceList
FAIL: NIECONN_REFUSED (Connection refused), NiRawConnect failed in plugin_fopen()

Edit the ASCS and ERS profiles

On either server, switch to the profile directory, by using either of the following commands:
```
# cd /usr/sap/SID/SYS/profile
```
```
# cd /sapmnt/SID/profile
```
If necessary, you can find the files names of your ASCS and ERS profiles by listing the files in the profile directory or use the following formats:
```
SID_ASCSASCS_INSTANCE_NUMBER_ASCS_VIRTUAL_HOST_NAME
```
```
SID_ERSERS_INSTANCE_NUMBER_ERS_VIRTUAL_HOST_NAME
```

Enable the package sap-suse-cluster-connector by adding the following lines to the profiles ASCS and ERS instance profiles:

#-----------------------------------------------------------------------
# SUSE HA library
#-----------------------------------------------------------------------
service/halib = $(DIR_CT_RUN)/saphascriptco.so
service/halib_cluster_connector = /usr/bin/sap_suse_cluster_connector

If you are using ENSA1, enable the keepalive function by setting the following in the ASCS profile:
```
enque/encni/set_so_keepalive = true
```
For more information, see SAP Note 1410736 - TCP/IP: setting keepalive interval.
If necessary, edit the ASCS and ERS profiles to change the startup behavior of the Enqueue Server and the Enqueue Replication Server.
ENSA1
In the "Start SAP enqueue server" section of the ASCS profile, if you see Restart_Program_NN, change "Restart" to "Start", as shown in the following example.
```
Start_Program_01 = local $(_EN) pf=$(_PF)
```
In the "Start enqueue replication server" section of the ERS profile, if you see Restart_Program_NN, change "Restart" to "Start", as shown in the following example.
```
Start_Program_00 = local $(_ER) pf=$(_PFL) NR=$(SCSID)
```
ENSA2
In the "Start SAP enqueue server" section of the ASCS profile, if you see Restart_Program_NN, change "Restart" to "Start", as shown in the following example.
```
Start_Program_01 = local $(_ENQ) pf=$(_PF)
```
In the "Start enqueue replicator" section of the ERS profile, if you see Restart_Program_NN, change "Restart" to "Start", as shown in the following example.
```
Start_Program_00 = local $(_ENQR) pf=$(_PF) ...
```

Add the `sidadm` user to the `haclient` user group

When you installed the sap-suse-cluster-connector, the installation created an haclient user group. To enable the SID_LCadm user to work with the cluster, add it to the haclient user group.

On both servers, add the SID_LCadm user to the haclient user group:
```
# usermod -aG haclient SID_LCadm
```

Configure the cluster resources for ASCS and ERS

As root from either server, place the cluster in maintenance mode:
```
# crm configure property maintenance-mode="true"
```

Confirm that the custer is in maintenance mode:

# crm status

If the cluster is in maintenance mode, the status includes the following lines:

              *** Resource management is DISABLED ***
The cluster will not attempt to start, stop or recover services

Create the cluster resources for the ASCS and ERS services:

ENSA1

Create the cluster resource for the ASCS instance. The value of InstanceName is the name of the instance profile that SWPM generated when you installed ASCS.

# crm configure primitive ASCS_INSTANCE_RSC_NAME SAPInstance \
  operations \$id=ASCS_INSTANCE_RSC_OPERATIONS_NAME \
  op monitor interval=11 timeout=60 on-fail=restart \
  params InstanceName=SID_ASCSASCS_INSTANCE_NUMBER_ASCS_VIRTUAL_HOST_NAME \
     START_PROFILE="/PATH_TO_PROFILE/SID_ASCSASCS_INSTANCE_NUMBER_ASCS_VIRTUAL_HOST_NAME" \
     AUTOMATIC_RECOVER=false \
  meta resource-stickiness=5000 failure-timeout=60 \
     migration-threshold=1 priority=10

Create the cluster resource for the ERS instance. The value of InstanceName is the name of the instance profile that SWPM generated when you installed ERS. The parameter IS_ERS=true tells Pacemaker to set the runsersSID flag to 1 on the node where ERS is active.

# crm configure primitive ERS_INSTANCE_RSC_NAME SAPInstance \
  operations \$id=ERS_INSTANCE_RSC_OPERATIONS_NAME \
  op monitor interval=11 timeout=60 on-fail=restart \
  params InstanceName=SID_ERSERS_INSTANCE_NUMBER_ERS_VIRTUAL_HOST_NAME \
     START_PROFILE="/PATH_TO_PROFILE/SID_ERSERS_INSTANCE_NUMBER_ERS_VIRTUAL_HOST_NAME" \
     AUTOMATIC_RECOVER=false IS_ERS=true \
  meta priority=1000

ENSA2

Create the cluster resource for the ASCS instance. The value of InstanceName is the name of the instance profile that SWPM generated when you installed ASCS.

# crm configure primitive ASCS_INSTANCE_RSC_NAME SAPInstance \
  operations \$id=ASCS_INSTANCE_RSC_OPERATIONS_NAME \
  op monitor interval=11 timeout=60 on-fail=restart \
  params InstanceName=SID_ASCSASCS_INSTANCE_NUMBER_ASCS_VIRTUAL_HOST_NAME \
     START_PROFILE="/PATH_TO_PROFILE/SID_ASCSASCS_INSTANCE_NUMBER_ASCS_VIRTUAL_HOST_NAME" \
     AUTOMATIC_RECOVER=false \
  meta resource-stickiness=5000 failure-timeout=60

Create the cluster resource for the ERS instance. The value of InstanceName is the name of the instance profile that SWPM generated when you installed ERS.

# crm configure primitive ERS_INSTANCE_RSC_NAME SAPInstance \
  operations \$id=ERS_INSTANCE_RSC_OPERATIONS_NAME \
  op monitor interval=11 timeout=60 on-fail=restart \
  params InstanceName=SID_ERSERS_INSTANCE_NUMBER_ERS_VIRTUAL_HOST_NAME  \
     START_PROFILE="/PATH_TO_PROFILE/SID_ERSERS_INSTANCE_NUMBER_ERS_VIRTUAL_HOST_NAME" \
     AUTOMATIC_RECOVER=false IS_ERS=true

Configure the resource groups and location constraints

Group the ASCS and ERS resources. You can display the names of all your previously defined resources by entering the command crm resource status:
```
# crm configure group ASCS_RSC_GROUP_NAME ASCS_FILE_SYSTEM_RSC_NAME \
  ASCS_HEALTH_CHECK_RSC_NAME ASCS_VIP_RSC_NAME \
  ASCS_INSTANCE_RSC_NAME \
  meta resource-stickiness=3000
```
Replace the following:
- ASCS_RESOURCE_GROUP: specify a unique group name for the ASCS cluster resources. You can ensure uniqueness by using a convention like "SID_ASCSinstance number_group". For example, nw1_ASCS00_group.
- ASCS_FILE_SYSTEM_RESOURCE: specify the name of the cluster resource that you defined for the ASCS file system earlier.
- ASCS_HEALTH_CHECK_RESOURCE: specify the name of the cluster resource that you defined for the ASCS health check earlier.
- ASCS_VIP_RESOURCE: specify the name of the cluster resource that you defined for the ASCS VIP earlier.
- ASCS_INSTANCE_RESOURCE: specify the name of the cluster resource that you defined for the ASCS instance earlier.
```
# crm configure group ERS_RSC_GROUP_NAME ERS_FILE_SYSTEM_RSC_NAME \
  ERS_HEALTH_CHECK_RSC_NAME ERS_VIP_RSC_NAME \
  ERS_INSTANCE_RSC_NAME
```
Replace the following:
- ERS_RESOURCE_GROUP: specify a unique group name for the ERS cluster resources. You can ensure uniqueness by using a convention like "SID_ERSinstance number_group". For example, nw1_ERS10_group.
- ERS_FILE_SYSTEM_RESOURCE: specify the name of the cluster resource that you defined for the ERS file system earlier.
- ERS_HEALTH_CHECK_RESOURCE: specify the name of the cluster resource that you defined for the ERS health check earlier.
- ERS_VIP_RESOURCE: specify the name of the cluster resource that you defined for the ERS VIP earlier.
- ERS_INSTANCE_RESOURCE: specify the name of the cluster resource that you defined for the ERS instance earlier.

Create the colocation constraints:

ENSA1

Create a colocation constraint that prevents the ASCS resources from running on the same server as the ERS resources:
```
# crm configure colocation PREVENT_ASCS_ERS_COLOC -5000: ERS_RSC_GROUP_NAME ASCS_RSC_GROUP_NAME
```
Configure ASCS to failover to the server where ERS is running, as determined by the flag runsersSID being equal to 1:
```
# crm configure location LOC_ASCS_SID_FAILOVER_TO_ERS ASCS_INSTANCE_RSC_NAME \
rule 2000: runs_ers_SID eq 1
```

Configure ASCS to start before ERS moves to the other server after a failover:

# crm configure order ORD_SAP_SID_FIRST_START_ASCS \
 Optional: ASCS_INSTANCE_RSC_NAME:start \
 ERS_INSTANCE_RSC_NAME:stop symmetrical=false

ENSA2

Create a colocation constraint that prevents the ASCS resources from running on the same server as the ERS resources:
```
# crm configure colocation PREVENT_ASCS_ERS_COLOC -5000: ERS_RSC_GROUP_NAME ASCS_RSC_GROUP_NAME
```

Configure ASCS to start before ERS moves to the other server after a failover:

# crm configure order ORD_SAP_SID_FIRST_START_ASCS \
 Optional: ASCS_INSTANCE_RSC_NAME:start \
 ERS_INSTANCE_RSC_NAME:stop symmetrical=false

Disable maintenance mode.

# crm configure property maintenance-mode="false"

Check the configuration of the groups, colocation constraints, and ordering:

# crm config show

The output should include lines similar to those in the following example:

ENSA1

group ers-aha-rsc-group-name filesystem-rsc-nw-aha-ers health-check-rsc-nw-ha-ers vip-rsc-nw-aha-ers ers-aha-instance-rsc-name
group scs-aha-rsc-group-name filesystem-rsc-nw-aha-scs health-check-rsc-nw-ha-scs vip-rsc-nw-aha-scs scs-aha-instance-rsc-name \
        meta resource-stickiness=3000
colocation prevent-aha-scs-ers-coloc -5000: ers-aha-rsc-group-name scs-aha-rsc-group-name
location fencing-rsc-nw-aha-vm-1-loc fencing-rsc-nw-aha-vm-1 -inf: nw-ha-vm-1
location fencing-rsc-nw-aha-vm-2-loc fencing-rsc-nw-aha-vm-2 -inf: nw-ha-vm-2
location loc-sap-AHA-failover-to-ers scs-aha-instance-rsc-name \
        rule 2000: runs_ers_AHA eq 1

ENSA2

group ers-aha-rsc-group-name filesystem-rsc-nw-aha-ers health-check-rsc-nw-ha-ers vip-rsc-nw-aha-ers ers-aha-instance-rsc-name
group scs-aha-rsc-group-name filesystem-rsc-nw-aha-scs health-check-rsc-nw-ha-scs vip-rsc-nw-aha-scs scs-aha-instance-rsc-name \
        meta resource-stickiness=3000
location fencing-location-nw-aha-vm-1 fencing-rsc-nw-aha-vm-1 -inf: nw-ha-vm-1
location fencing-location-nw-aha-vm-2 fencing-rsc-nw-aha-vm-2 -inf: nw-ha-vm-2
order ord-sap-AHA-first-start-ascs Optional: scs-aha-instance-rsc-name:start ers-aha-instance-rsc-name:stop symmetrical=false
colocation prevent-aha-scs-ers-coloc -5000: ers-aha-rsc-group-name scs-aha-rsc-group-name

Validate and test your cluster

This section shows you how to run the following tests:

Check for configuration errors
Confirm that the ASCS and ERS resources switch servers correctly during failovers
Confirm that locks are retained
Simulate a Compute Engine maintenance event to make sure that live migration doesn't trigger a failover

Check the cluster configuration

As root on either server, check which nodes your resources are running on:

# crm status

In the following example, the ASCS resources are running on the nw-ha-vm-1 server and the ERS resources are running on the nw-ha-vm-2 server.

Cluster Summary:
  * Stack: corosync
  * Current DC: nw-ha-vm-2 (version 2.0.4+20200616.2deceaa3a-3.3.1-2.0.4+20200616.2deceaa3a) - partition with quorum
  * Last updated: Thu May 20 16:58:46 2021
  * Last change:  Thu May 20 16:57:31 2021 by ahaadm via crm_resource on nw-ha-vm-2
  * 2 nodes configured
  * 10 resource instances configured

Node List:
  * Online: [ nw-ha-vm-1 nw-ha-vm-2 ]

Active Resources:
  * fencing-rsc-nw-aha-vm-1     (stonith:fence_gce):     Started nw-ha-vm-2
  * fencing-rsc-nw-aha-vm-2     (stonith:fence_gce):     Started nw-ha-vm-1
  * Resource Group: ascs-aha-rsc-group-name:
    * filesystem-rsc-nw-aha-ascs (ocf::heartbeat:Filesystem):     Started nw-ha-vm-1
    * health-check-rsc-nw-ha-ascs        (ocf::heartbeat:anything):       Started nw-ha-vm-1
    * vip-rsc-nw-aha-ascs        (ocf::heartbeat:IPaddr2):        Started nw-ha-vm-1
    * ascs-aha-instance-rsc-name (ocf::heartbeat:SAPInstance):    Started nw-ha-vm-1
  * Resource Group: ers-aha-rsc-group-name:
    * filesystem-rsc-nw-aha-ers (ocf::heartbeat:Filesystem):     Started nw-ha-vm-2
    * health-check-rsc-nw-ha-ers        (ocf::heartbeat:anything):       Started nw-ha-vm-2
    * vip-rsc-nw-aha-ers        (ocf::heartbeat:IPaddr2):        Started nw-ha-vm-2
    * ers-aha-instance-rsc-name (ocf::heartbeat:SAPInstance):    Started nw-ha-vm-2

Switch to the SID_LCadm user:
```
# su - SID_LCadm
```

Check the cluster configuration. For INSTANCE_NUMBER, specify the instance number of the ASCS or ERS instance that is active on the server where you are entering the command:

> sapcontrol -nr INSTANCE_NUMBER -function HAGetFailoverConfig

HAActive should be TRUE, as shown in the following example:

20.05.2021 01:33:25
HAGetFailoverConfig
OK
HAActive: TRUE
HAProductVersion: SUSE Linux Enterprise Server for SAP Applications 15 SP2
HASAPInterfaceVersion: SUSE Linux Enterprise Server for SAP Applications 15 SP2 (sap_suse_cluster_connector 3.1.2)
HADocumentation: https://www.suse.com/products/sles-for-sap/resource-library/sap-best-practices/
HAActiveNode: nw-ha-vm-1
HANodes: nw-ha-vm-1, nw-ha-vm-2

As SID_LCadm, check for errors in the configuration:

> sapcontrol -nr INSTANCE_NUMBER -function HACheckConfig

You should see output similar to the following example:

20.05.2021 01:37:19
HACheckConfig
OK
state, category, description, comment
SUCCESS, SAP CONFIGURATION, Redundant ABAP instance configuration, 0 ABAP instances detected
SUCCESS, SAP CONFIGURATION, Redundant Java instance configuration, 0 Java instances detected
SUCCESS, SAP CONFIGURATION, Enqueue separation, All Enqueue server separated from application server
SUCCESS, SAP CONFIGURATION, MessageServer separation, All MessageServer separated from application server
SUCCESS, SAP STATE, SCS instance running, SCS instance status ok
SUCCESS, SAP CONFIGURATION, SAPInstance RA sufficient version (vh-ascs-aha_AHA_00), SAPInstance includes is-ers patch
SUCCESS, SAP CONFIGURATION, Enqueue replication (vh-ascs-aha_AHA_00), Enqueue replication enabled
SUCCESS, SAP STATE, Enqueue replication state (vh-ascs-aha_AHA_00), Enqueue replication active

On the server where ASCS is active, as SID_LCadm, simulate a failover:

> sapcontrol -nr ASCS_INSTANCE_NUMBER -function HAFailoverToNode ""

As root, if you follow the failover by using crm_mon, you should see ASCS move to the other server, ERS stop on that server, and then ERS move to the server that ASCS used to be running on.

Simulate a failover

Test your cluster by simulating a failure on the primary host. Use a test system or run the test on your production system before you release the system for use.

You can simulate a failure in a variety of ways, including:

shutdown -r (on the active node)
ip link set eth0 down
echo c > /proc/sysrq-trigger

These instructions use ip link set eth0 down to take the network interface offline, because it validates both failover as well as fencing.

Backup your system.
As root on the host with the active SCS instance, take the network interface offline:
```
# ip link set eth0 down
```
Reconnect to either host using SSH and change to the root user.

Enter crm status to confirm that the primary host is now active on the VM that used to contain the secondary host. Automatic restart is enabled in the cluster, so the stopped host will restart and assume the role of secondary host, as shown in the following example.

Cluster Summary:
* Stack: corosync
* Current DC: nw-ha-vm-2 (version 2.0.4+20200616.2deceaa3a-3.3.1-2.0.4+20200616.2deceaa3a) - partition with quorum
* Last updated: Fri May 21 22:31:32 2021
* Last change:  Thu May 20 20:36:36 2021 by ahaadm via crm_resource on nw-ha-vm-1
* 2 nodes configured
* 10 resource instances configured

Node List:
* Online: [ nw-ha-vm-1 nw-ha-vm-2 ]

Full List of Resources:
* fencing-rsc-nw-aha-vm-1     (stonith:fence_gce):     Started nw-ha-vm-2
* fencing-rsc-nw-aha-vm-2     (stonith:fence_gce):     Started nw-ha-vm-1
* Resource Group: scs-aha-rsc-group-name:
  * filesystem-rsc-nw-aha-scs (ocf::heartbeat:Filesystem):     Started nw-ha-vm-2
  * health-check-rsc-nw-ha-scs        (ocf::heartbeat:anything):       Started nw-ha-vm-2
  * vip-rsc-nw-aha-scs        (ocf::heartbeat:IPaddr2):        Started nw-ha-vm-2
  * scs-aha-instance-rsc-name (ocf::heartbeat:SAPInstance):    Started nw-ha-vm-2
* Resource Group: ers-aha-rsc-group-name:
  * filesystem-rsc-nw-aha-ers (ocf::heartbeat:Filesystem):     Started nw-ha-vm-1
  * health-check-rsc-nw-ha-ers        (ocf::heartbeat:anything):       Started nw-ha-vm-1
  * vip-rsc-nw-aha-ers        (ocf::heartbeat:IPaddr2):        Started nw-ha-vm-1
  * ers-aha-instance-rsc-name (ocf::heartbeat:SAPInstance):    Started nw-ha-vm-1

Confirm lock entries are retained

To confirm lock entries are preserved across a failover, first select the tab for your version of the Enqueue Server and the follow the procedure to generate lock entries, simulate a failover, and confirm that the lock entries are retained after ASCS is activated again.

ENSA1

As SID_LCadm, on the server where ERS is active, generate lock entries by using the enqt program:

> enqt pf=/PATH_TO_PROFILE/SID_ERSERS_INSTANCE_NUMBER_ERS_VIRTUAL_HOST_NAME 11 NUMBER_OF_LOCKS

As SID_LCadm, on the server where ASCS is active, verify that the lock entries are registered:
```
> sapcontrol -nr ASCS_INSTANCE_NUMBER -function EnqGetStatistic | grep locks_now
```
If you created 10 locks, you should see output similar to the following example:
```
locks_now: 10
```

As SID_LCadm, on the server where ERS is active, start the monitoring function, OpCode=20, of the enqt program:

> enqt pf=/PATH_TO_PROFILE/SID_ERSERS_INSTANCE_NUMBER_ERS_VIRTUAL_HOST_NAME 20 1 1 9999

For example:

> enqt pf=/sapmnt/AHA/profile/AHA_ERS10_vh-ers-aha 20 1 1 9999

Where ASCS is active, reboot the server.

On the monitoring server, by the time Pacemaker stops ERS to move it to the other server, you should see output similar to the following.
```
Number of selected entries: 10
Number of selected entries: 10
Number of selected entries: 10
Number of selected entries: 10
Number of selected entries: 10
```
When the enqt monitor stops, exit the monitor by entering Ctrl + c.
Optionally, as root on either server, monitor the cluster failover:
```
# crm_mon
```

As SID_LCadm, after you confirm the locks were retained, release the locks:

> enqt pf=/PATH_TO_PROFILE/SID_ERSERS_INSTANCE_NUMBER_ERS_VIRTUAL_HOST_NAME 12 NUMBER_OF_LOCKS

As SID_LCadm, on the server where ASCS is active, verify that the lock entries are removed:
```
> sapcontrol -nr ASCS_INSTANCE_NUMBER -function EnqGetStatistic | grep locks_now
```

ENSA2

As SID_LCadm, on the server where ASCS is active, generate lock entries by using the enq_adm program:

> enq_admin --set_locks=NUMBER_OF_LOCKS:X:DIAG::TAB:%u pf=/PATH_TO_PROFILE/SID_ASCSASCS_INSTANCE_NUMBER_ASCS_VIRTUAL_HOST_NAME

As SID_LCadm, on the server where ASCS is active, verify that the lock entries are registered:
```
> sapcontrol -nr ASCS_INSTANCE_NUMBER -function EnqGetStatistic | grep locks_now
```
If you created 10 locks, you should see output similar to the following example:
```
locks_now: 10
```
Where ERS is active, confirm that the lock entries were replicated:
```
> sapcontrol -nr ERS_INSTANCE_NUMBER -function EnqGetStatistic | grep locks_now
```
The number of returned locks should be the same as on the ASCS instance.
Where ASCS is active, reboot the server.
Optionally, as root on either server, monitor the cluster failover:
```
# crm_mon
```
As SID_LCadm, on the server where ASCS was restarted, verify that the lock entries were retained:
```
> sapcontrol -nr ASCS_INSTANCE_NUMBER -function EnqGetStatistic | grep locks_now
```

As SID_LCadm, on the server where ERS is active, after you confirm the locks were retained, release the locks:

> enq_admin --release_locks=NUMBER_OF_LOCKS:X:DIAG::TAB:%u pf=/PATH_TO_PROFILE/SID_ERSERS_INSTANCE_NUMBER_ERS_VIRTUAL_HOST_NAME

As SID_LCadm, on the server where ASCS is active, verify that the lock entries are removed:
```
> sapcontrol -nr ASCS_INSTANCE_NUMBER -function EnqGetStatistic | grep locks_now
```
You should see output similar to the following example:
```
locks_now: 0
```

Simulate a Compute Engine maintenance event

Simulate a Compute Engine maintenance event to make sure that live migration does not trigger a failover.

The timeout and interval values that are used in these instructions account for the duration of live migrations. If you use shorter values in your cluster configuration, the risk that live migration might trigger a failover is greater.

To test the tolerance of your cluster for live migration:

On the primary node, trigger a simulated maintenance event by using following gcloud CLI command:
```
# gcloud compute instances simulate-maintenance-event PRIMARY_VM_NAME
```
Confirm that the primary node does not change:
```
# crm status
```

Evaluate your SAP NetWeaver workload

To automate continuous validation checks for your SAP NetWeaver high-availability workloads running on Google Cloud, you can use Workload Manager.

Workload Manager allows you to automatically scan and evaluate your SAP NetWeaver high-availability workloads against best practices from SAP, Google Cloud, and OS vendors. This helps improve the quality, performance, and reliability of your workloads.

For information about the best practices that Workload Manager supports for evaluating SAP NetWeaver high-availability workloads running on Google Cloud, see Workload Manager best practices for SAP. For information about creating and running an evaluation using Workload Manager, see Create and run an evaluation.

Troubleshooting

To troubleshoot problems with high-availability configurations for SAP NetWeaver, see Troubleshooting high-availability configurations for SAP.

Collect diagnostic information for SAP NetWeaver high-availability clusters

If you need help resolving a problem with high-availability clusters for SAP NetWeaver, gather the required diagnostic information and contact Cloud Customer Care.

To collect diagnostic information, see High-availability clusters on SLES diagnostic information.

Support

For issues with Google Cloud infrastructure or services, contact Customer Care. You can find contact information on the Support Overview page in the Google Cloud console. If Customer Care determines that a problem resides in your SAP systems, you are referred to SAP Support.

For SAP product-related issues, log your support request with SAP support. SAP evaluates the support ticket and, if it appears to be a Google Cloud infrastructure issue, transfers the ticket to the Google Cloud component BC-OP-LNX-GOOGLE or BC-OP-NT-GOOGLE.

Support requirements

Before you can receive support for SAP systems and the Google Cloud infrastructure and services that they use, you must meet the minimum support plan requirements.

For more information about the minimum support requirements for SAP on Google Cloud, see:

Getting support for SAP on Google Cloud
SAP Note 2456406 - SAP on Google Cloud Platform: Support Prerequisites (An SAP user account is required)

Performing post-deployment tasks

Before using your SAP NetWeaver system, we recommend that you backup your new SAP NetWeaver HA system.

For more information, see SAP NetWeaver operations guide.

What's next

For more information high-availability, SAP NetWeaver, and Google Cloud, see the following resources:

SUSE Best Practices

High-availability planning guide for SAP NetWeaver on Google Cloud
For more information about VM administration and monitoring, see the SAP NetWeaver Operations Guide

Terraform: HA cluster configuration guide for SAP NetWeaver on SLES

The system that this guide deploys

Prerequisites

Related information from SUSE

Creating a network

Setting up a NAT gateway

Adding firewall rules

Creating a high-availability Linux cluster for SAP NetWeaver

Verifying the deployment of your SAP NetWeaver HA system

Check the logs

Logs Explorer

Legacy Logs Viewer

Check the configuration of the VM

Validate your installation of Google Cloud's Agent for SAP

Verify that Google Cloud's Agent for SAP is running

Verify that SAP Host Agent is receiving metrics

Install ASCS and ERS

Prepare for installation

Install the ASCS component

Install the ERS component

Configure the SAP services

Confirm the SAP service entries

systemV

systemd

Stop the SAP services

Edit the ASCS and ERS profiles

ENSA1

ENSA2

Add the sidadm user to the haclient user group

Configure the cluster resources for ASCS and ERS

ENSA1

ENSA2

Configure the resource groups and location constraints

ENSA1

ENSA2

ENSA1

ENSA2

Validate and test your cluster

Check the cluster configuration

Simulate a failover

Confirm lock entries are retained

ENSA1

ENSA2

Simulate a Compute Engine maintenance event

Evaluate your SAP NetWeaver workload

Troubleshooting

Collect diagnostic information for SAP NetWeaver high-availability clusters

Support

Support requirements

Performing post-deployment tasks

What's next

`systemV`

`systemd`

Add the `sidadm` user to the `haclient` user group