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High availability for SAP HANA scale-out system with HSR on SUSE Linux Enterprise Server

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This article describes how to deploy a highly available SAP HANA system in a scale-out configuration with HANA system replication (HSR) and Pacemaker on Azure SUSE Linux Enterprise Server virtual machines (VMs). The shared file systems in the presented architecture are NFS mounted and are provided by Azure NetApp Files or NFS share on Azure Files.

In the example configurations, installation commands, and so on, the HANA instance is 03 and the HANA system ID is HN1.

Before you begin, refer to the following SAP notes and papers:

Overview

One method to achieve HANA high availability for HANA scale-out installations, is to configure HANA system replication and protect the solution with Pacemaker cluster to allow automatic failover. When an active node fails, the cluster fails over the HANA resources to the other site.
The presented configuration shows three HANA nodes on each site, plus majority maker node to prevent split-brain scenario. The instructions can be adapted, to include more VMs as HANA DB nodes.

The HANA shared file system /hana/shared in the presented architecture can be provided by Azure NetApp Files or NFS share on Azure Files. The HANA shared file system is NFS mounted on each HANA node in the same HANA system replication site. File systems /hana/data and /hana/log are local file systems and aren't shared between the HANA DB nodes. SAP HANA will be installed in non-shared mode.

For recommended SAP HANA storage configurations, see SAP HANA Azure VMs storage configurations.

Important

If deploying all HANA file systems on Azure NetApp Files, for production systems, where performance is a key, we recommend to evaluate and consider using Azure NetApp Files application volume group for SAP HANA.

Warning

Deploying /hana/data and /hana/log on NFS on Azure Files is not supported.

SAP HANA scale-out with HSR and Pacemaker cluster on SLES

In the preceding diagram, three subnets are represented within one Azure virtual network, following the SAP HANA network recommendations:

  • for client communication - client 10.23.0.0/24
  • for internal HANA inter-node communication - inter 10.23.1.128/26
  • for HANA system replication - hsr 10.23.1.192/26

As /hana/data and /hana/log are deployed on local disks, it isn't necessary to deploy separate subnet and separate virtual network cards for communication to the storage.

If you're using Azure NetApp Files, the NFS volumes for /hana/shared, are deployed in a separate subnet, delegated to Azure NetApp Files: anf 10.23.1.0/26.

Prepare the infrastructure

In the instructions that follow, we assume that you've already created the resource group, the Azure virtual network with three Azure network subnets: client, inter and hsr.

Deploy Linux virtual machines via the Azure portal

  1. Deploy the Azure VMs.

    For the configuration presented in this document, deploy seven virtual machines:

    • three virtual machines to serve as HANA DB nodes for HANA replication site 1: hana-s1-db1, hana-s1-db2 and hana-s1-db3
    • three virtual machines to serve as HANA DB nodes for HANA replication site 2: hana-s2-db1, hana-s2-db2 and hana-s2-db3
    • a small virtual machine to serve as majority maker: hana-s-mm

    The VMs, deployed as SAP DB HANA nodes should be certified by SAP for HANA as published in the SAP HANA Hardware directory. When deploying the HANA DB nodes, make sure that Accelerated Network is selected.

    For the majority maker node, you can deploy a small VM, as this VM doesn't run any of the SAP HANA resources. The majority maker VM is used in the cluster configuration to achieve odd number of cluster nodes in a split-brain scenario. The majority maker VM only needs one virtual network interface in the client subnet in this example.

    Deploy local managed disks for /hana/data and /hana/log. The minimum recommended storage configuration for /hana/data and /hana/log is described in SAP HANA Azure VMs storage configurations.

    Deploy the primary network interface for each VM in the client virtual network subnet.
    When the VM is deployed via Azure portal, the network interface name is automatically generated. In these instructions for simplicity we'll refer to the automatically generated, primary network interfaces, which are attached to the client Azure virtual network subnet as hana-s1-db1-client, hana-s1-db2-client, hana-s1-db3-client, and so on.

    Important

    • Make sure that the OS you select is SAP-certified for SAP HANA on the specific VM types you're using. For a list of SAP HANA certified VM types and OS releases for those types, go to the SAP HANA certified IaaS platforms site. Click into the details of the listed VM type to get the complete list of SAP HANA-supported OS releases for that type.
    • If you choose to deploy /hana/shared on NFS on Azure Files, we recommend to deploy on SLES 15 SP2 and above.

  2. Create six network interfaces, one for each HANA DB virtual machine, in the inter virtual network subnet (in this example, hana-s1-db1-inter, hana-s1-db2-inter, hana-s1-db3-inter, hana-s2-db1-inter, hana-s2-db2-inter, and hana-s2-db3-inter).

  3. Create six network interfaces, one for each HANA DB virtual machine, in the hsr virtual network subnet (in this example, hana-s1-db1-hsr, hana-s1-db2-hsr, hana-s1-db3-hsr, hana-s2-db1-hsr, hana-s2-db2-hsr, and hana-s2-db3-hsr).

  4. Attach the newly created virtual network interfaces to the corresponding virtual machines:

    1. Go to the virtual machine in the Azure portal.
    2. In the left pane, select Virtual Machines. Filter on the virtual machine name (for example, hana-s1-db1), and then select the virtual machine.
    3. In the Overview pane, select Stop to deallocate the virtual machine.
    4. Select Networking, and then attach the network interface. In the Attach network interface drop-down list, select the already created network interfaces for the inter and hsr subnets.
    5. Select Save.
    6. Repeat steps b through e for the remaining virtual machines (in our example, hana-s1-db2, hana-s1-db3, hana-s2-db1, hana-s2-db2 and hana-s2-db3).
    7. Leave the virtual machines in stopped state for now. Next, we'll enable accelerated networking for all newly attached network interfaces.

  5. Enable accelerated networking for the additional network interfaces for the inter and hsr subnets by doing the following steps:

    1. Open Azure Cloud Shell in the Azure portal.

    2. Execute the following commands to enable accelerated networking for the additional network interfaces, which are attached to the inter and hsr subnets.

      az network nic update --id /subscriptions/your subscription/resourceGroups/your resource group/providers/Microsoft.Network/networkInterfaces/hana-s1-db1-inter --accelerated-networking true
az network nic update --id /subscriptions/your subscription/resourceGroups/your resource group/providers/Microsoft.Network/networkInterfaces/hana-s1-db2-inter --accelerated-networking true
az network nic update --id /subscriptions/your subscription/resourceGroups/your resource group/providers/Microsoft.Network/networkInterfaces/hana-s1-db3-inter --accelerated-networking true
az network nic update --id /subscriptions/your subscription/resourceGroups/your resource group/providers/Microsoft.Network/networkInterfaces/hana-s2-db1-inter --accelerated-networking true
az network nic update --id /subscriptions/your subscription/resourceGroups/your resource group/providers/Microsoft.Network/networkInterfaces/hana-s2-db2-inter --accelerated-networking true
az network nic update --id /subscriptions/your subscription/resourceGroups/your resource group/providers/Microsoft.Network/networkInterfaces/hana-s2-db3-inter --accelerated-networking true

az network nic update --id /subscriptions/your subscription/resourceGroups/your resource group/providers/Microsoft.Network/networkInterfaces/hana-s1-db1-hsr --accelerated-networking true
az network nic update --id /subscriptions/your subscription/resourceGroups/your resource group/providers/Microsoft.Network/networkInterfaces/hana-s1-db2-hsr --accelerated-networking true
az network nic update --id /subscriptions/your subscription/resourceGroups/your resource group/providers/Microsoft.Network/networkInterfaces/hana-s1-db3-hsr --accelerated-networking true
az network nic update --id /subscriptions/your subscription/resourceGroups/your resource group/providers/Microsoft.Network/networkInterfaces/hana-s2-db1-hsr --accelerated-networking true
az network nic update --id /subscriptions/your subscription/resourceGroups/your resource group/providers/Microsoft.Network/networkInterfaces/hana-s2-db2-hsr --accelerated-networking true
az network nic update --id /subscriptions/your subscription/resourceGroups/your resource group/providers/Microsoft.Network/networkInterfaces/hana-s2-db3-hsr --accelerated-networking true

  6. Start the HANA DB virtual machines

Configure Azure load balancer

During VM configuration, you have an option to create or select exiting load balancer in networking section. Follow below steps, to setup standard load balancer for high availability setup of HANA database.

Note

  • For HANA scale out, select the NIC for the client subnet when adding the virtual machines in the backend pool.
  • The full set of command in Azure CLI and PowerShell adds the VMs with primary NIC in the backend pool.

Follow the steps in Create load balancer to set up a standard load balancer for a high-availability SAP system by using the Azure portal. During the setup of the load balancer, consider the following points:

  1. Frontend IP Configuration: Create a front-end IP. Select the same virtual network and subnet name as your database virtual machines.
  2. Backend Pool: Create a back-end pool and add database VMs.
  3. Inbound rules: Create a load-balancing rule. Follow the same steps for both load-balancing rules.
    • Frontend IP address: Select a front-end IP.
    • Backend pool: Select a back-end pool.
    • High-availability ports: Select this option.
    • Protocol: Select TCP.
    • Health Probe: Create a health probe with the following details:
      • Protocol: Select TCP.
      • Port: For example, 625<instance-no.>.
      • Interval: Enter 5.
      • Probe Threshold: Enter 2.
    • Idle timeout (minutes): Enter 30.
    • Enable Floating IP: Select this option.

Note

The health probe configuration property numberOfProbes, otherwise known as Unhealthy threshold in the portal, isn't respected. To control the number of successful or failed consecutive probes, set the property probeThreshold to 2. It's currently not possible to set this property by using the Azure portal, so use either the Azure CLI or the PowerShell command.

Note

When VMs without public IP addresses are placed in the backend pool of internal (no public IP address) Standard Azure load balancer, there will be no outbound internet connectivity, unless additional configuration is performed to allow routing to public end points. For details on how to achieve outbound connectivity see Public endpoint connectivity for Virtual Machines using Azure Standard Load Balancer in SAP high-availability scenarios.

Important

  • Do not enable TCP timestamps on Azure VMs placed behind Azure Load Balancer. Enabling TCP timestamps will cause the health probes to fail. Set parameter net.ipv4.tcp_timestamps to 0. For details see Load Balancer health probes and SAP note 2382421.
  • To prevent saptune from changing the manually set net.ipv4.tcp_timestamps value from 0 back to 1, update saptune version to 3.1.1 or higher. For more details, see saptune 3.1.1 – Do I Need to Update?.

Deploy NFS

There are two options for deploying Azure native NFS for /hana/shared. You can deploy NFS volume on Azure NetApp Files or NFS share on Azure Files. Azure files support NFSv4.1 protocol, NFS on Azure NetApp files supports both NFSv4.1 and NFSv3.

The next sections describe the steps to deploy NFS - you'll need to select only one of the options.

Tip

You chose to deploy /hana/shared on NFS share on Azure Files or NFS volume on Azure NetApp Files.

Deploy the Azure NetApp Files infrastructure

Deploy Azure NetApp Files volumes for the /hana/shared file system. You'll need a separate /hana/shared volume for each HANA system replication site. For more information, see Set up the Azure NetApp Files infrastructure.

In this example, the following Azure NetApp Files volumes were used:

  • volume HN1-shared-s1 (nfs://10.23.1.7/HN1-shared-s1)
  • volume HN1-shared-s2 (nfs://10.23.1.7/HN1-shared-s2)

Deploy the NFS on Azure Files infrastructure

Deploy Azure Files NFS shares for the /hana/shared file system. You'll need a separate /hana/shared Azure Files NFS share for each HANA system replication site. For more information, see How to create an NFS share.

In this example, the following Azure Files NFS shares were used:

  • share hn1-shared-s1 (sapnfsafs.file.core.windows.net:/sapnfsafs/hn1-shared-s1)
  • share hn1-shared-s2 (sapnfsafs.file.core.windows.net:/sapnfsafs/hn1-shared-s2)

Operating system configuration and preparation

The instructions in the next sections are prefixed with one of the following abbreviations:

  • [A]: Applicable to all nodes, including majority maker
  • [AH]: Applicable to all HANA DB nodes
  • [M]: Applicable to the majority maker node only
  • [AH1]: Applicable to all HANA DB nodes on SITE 1
  • [AH2]: Applicable to all HANA DB nodes on SITE 2
  • [1]: Applicable only to HANA DB node 1, SITE 1
  • [2]: Applicable only to HANA DB node 1, SITE 2

Configure and prepare your OS by doing the following steps:

  1. [A] Maintain the host files on the virtual machines. Include entries for all subnets. The following entries were added to /etc/hosts for this example.

    # Client subnet
10.23.0.19      hana-s1-db1
10.23.0.20      hana-s1-db2
10.23.0.21      hana-s1-db3
10.23.0.22      hana-s2-db1
10.23.0.23      hana-s2-db2
10.23.0.24      hana-s2-db3
10.23.0.25      hana-s-mm    

# Internode subnet
10.23.1.132     hana-s1-db1-inter
10.23.1.133     hana-s1-db2-inter
10.23.1.134     hana-s1-db3-inter
10.23.1.135     hana-s2-db1-inter
10.23.1.136     hana-s2-db2-inter
10.23.1.137     hana-s2-db3-inter

# HSR subnet
10.23.1.196     hana-s1-db1-hsr
10.23.1.197     hana-s1-db2-hsr
10.23.1.198     hana-s1-db3-hsr
10.23.1.199     hana-s2-db1-hsr
10.23.1.200     hana-s2-db2-hsr
10.23.1.201     hana-s2-db3-hsr

  2. [A] Create configuration file /etc/sysctl.d/ms-az.conf with Microsoft for Azure configuration settings.

    vi /etc/sysctl.d/ms-az.conf

# Add the following entries in the configuration file
net.ipv6.conf.all.disable_ipv6 = 1
net.ipv4.tcp_max_syn_backlog = 16348
net.ipv4.conf.all.rp_filter = 0
sunrpc.tcp_slot_table_entries = 128
vm.swappiness=10

    Tip

    Avoid setting net.ipv4.ip_local_port_range and net.ipv4.ip_local_reserved_ports explicitly in the sysctl configuration files to allow SAP Host Agent to manage the port ranges. For more information, see SAP note 2382421.

  3. [A] SUSE delivers special resource agents for SAP HANA and by default agents for SAP HANA scale-up are installed. Uninstall the packages for scale-up, if installed and install the packages for scenario SAP HANA scale-out. The step needs to be performed on all cluster VMs, including the majority maker.

    Note

    SAPHanaSR-ScaleOut version 0.181 or higher must be installed.

    # Uninstall scale-up packages and patterns
sudo zypper remove patterns-sap-hana
sudo zypper remove SAPHanaSR SAPHanaSR-doc yast2-sap-ha

# Install the scale-out packages and patterns
sudo zypper in SAPHanaSR-ScaleOut SAPHanaSR-ScaleOut-doc 
sudo zypper in -t pattern ha_sles

  4. [AH] Prepare the VMs - apply the recommended settings per SAP note 2205917 for SUSE Linux Enterprise Server for SAP Applications.

Prepare the file systems

You chose to deploy the SAP shared directories on NFS share on Azure Files or NFS volume on Azure NetApp Files.

Mount the shared file systems (Azure NetApp Files NFS)

In this example, the shared HANA file systems are deployed on Azure NetApp Files and mounted over NFSv4.1. Follow the steps in this section, only if you're using NFS on Azure NetApp Files.

  1. [AH] Prepare the OS for running SAP HANA on NetApp Systems with NFS, as described in SAP note 3024346 - Linux Kernel Settings for NetApp NFS. Create configuration file /etc/sysctl.d/91-NetApp-HANA.conf for the NetApp configuration settings.

    vi /etc/sysctl.d/91-NetApp-HANA.conf

# Add the following entries in the configuration file
net.core.rmem_max = 16777216
net.core.wmem_max = 16777216
net.ipv4.tcp_rmem = 4096 131072 16777216
net.ipv4.tcp_wmem = 4096 16384 16777216
net.core.netdev_max_backlog = 300000
net.ipv4.tcp_slow_start_after_idle=0
net.ipv4.tcp_no_metrics_save = 1
net.ipv4.tcp_moderate_rcvbuf = 1
net.ipv4.tcp_window_scaling = 1
net.ipv4.tcp_sack = 1

  2. [AH] Adjust the sunrpc settings, as recommended in SAP note 3024346 - Linux Kernel Settings for NetApp NFS.

    vi /etc/modprobe.d/sunrpc.conf

# Insert the following line
options sunrpc tcp_max_slot_table_entries=128

  3. [AH] Create mount points for the HANA database volumes.

    mkdir -p /hana/shared

  4. [AH] Verify the NFS domain setting. Make sure that the domain is configured as the default Azure NetApp Files domain, that is, defaultv4iddomain.com and the mapping is set to nobody.
    This step is only needed, if using Azure NetAppFiles NFSv4.1.

    Important

    Make sure to set the NFS domain in /etc/idmapd.conf on the VM to match the default domain configuration on Azure NetApp Files: defaultv4iddomain.com. If there's a mismatch between the domain configuration on the NFS client (i.e. the VM) and the NFS server, i.e. the Azure NetApp configuration, then the permissions for files on Azure NetApp volumes that are mounted on the VMs will be displayed as nobody.

    sudo cat /etc/idmapd.conf
# Example
[General]
Domain = defaultv4iddomain.com
[Mapping]
Nobody-User = nobody
Nobody-Group = nobody

  5. [AH] Verify nfs4_disable_idmapping. It should be set to Y. To create the directory structure where nfs4_disable_idmapping is located, execute the mount command. You won't be able to manually create the directory under /sys/modules, because access is reserved for the kernel / drivers.
    This step is only needed, if using Azure NetAppFiles NFSv4.1.

    # Check nfs4_disable_idmapping 
cat /sys/module/nfs/parameters/nfs4_disable_idmapping
# If you need to set nfs4_disable_idmapping to Y
mkdir /mnt/tmp
mount 10.23.1.7:/HN1-share-s1 /mnt/tmp
umount  /mnt/tmp
echo "Y" > /sys/module/nfs/parameters/nfs4_disable_idmapping
# Make the configuration permanent
echo "options nfs nfs4_disable_idmapping=Y" >> /etc/modprobe.d/nfs.conf

  6. [AH1] Mount the shared Azure NetApp Files volumes on the SITE1 HANA DB VMs.

    sudo vi /etc/fstab
# Add the following entry
10.23.1.7:/HN1-shared-s1 /hana/shared nfs rw,nfsvers=4.1,hard,timeo=600,rsize=262144,wsize=262144,noatime,lock,_netdev,sec=sys  0  0
# Mount all volumes
sudo mount -a

  7. [AH2] Mount the shared Azure NetApp Files volumes on the SITE2 HANA DB VMs.

    sudo vi /etc/fstab
# Add the following entry
10.23.1.7:/HN1-shared-s2 /hana/shared nfs rw,nfsvers=4.1,hard,timeo=600,rsize=262144,wsize=262144,noatime,lock,_netdev,sec=sys  0  0
# Mount the volume
sudo mount -a

  8. [AH] Verify that the corresponding /hana/shared/ file systems are mounted on all HANA DB VMs with NFS protocol version NFSv4.1.

    sudo nfsstat -m
# Verify that flag vers is set to 4.1 
# Example from SITE 1, hana-s1-db1
/hana/shared from 10.23.1.7:/HN1-shared-s1
 Flags: rw,noatime,vers=4.1,rsize=262144,wsize=262144,namlen=255,hard,proto=tcp,timeo=600,retrans=2,sec=sys,clientaddr=10.23.0.19,local_lock=none,addr=10.23.1.7
# Example from SITE 2, hana-s2-db1
/hana/shared from 10.23.1.7:/HN1-shared-s2
 Flags: rw,noatime,vers=4.1,rsize=262144,wsize=262144,namlen=255,hard,proto=tcp,timeo=600,retrans=2,sec=sys,clientaddr=10.23.0.22,local_lock=none,addr=10.23.1.7

Mount the shared file systems (Azure Files NFS)

In this example, the shared HANA file systems are deployed on NFS on Azure Files. Follow the steps in this section, only if you're using NFS on Azure Files.

  1. [AH] Create mount points for the HANA database volumes.

    mkdir -p /hana/shared

  2. [AH1] Mount the shared Azure NetApp Files volumes on the SITE1 HANA DB VMs.

    sudo vi /etc/fstab
# Add the following entry
sapnfsafs.file.core.windows.net:/sapnfsafs/hn1-shared-s1 /hana/shared  nfs nfsvers=4.1,sec=sys  0  0
# Mount all volumes
sudo mount -a

  3. [AH2] Mount the shared Azure NetApp Files volumes on the SITE2 HANA DB VMs.

    sudo vi /etc/fstab
# Add the following entries
sapnfsafs.file.core.windows.net:/sapnfsafs/hn1-shared-s2 /hana/shared  nfs nfsvers=4.1,sec=sys  0  0
# Mount the volume
sudo mount -a

  4. [AH] Verify that the corresponding /hana/shared/ file systems are mounted on all HANA DB VMs with NFS protocol version NFSv4.1.

    sudo nfsstat -m
# Example from SITE 1, hana-s1-db1
sapnfsafs.file.core.windows.net:/sapnfsafs/hn1-shared-s1
 Flags: rw,relatime,vers=4.1,rsize=1048576,wsize=1048576,namlen=255,hard,proto=tcp,timeo=600,retrans=2,sec=sys,clientaddr=10.23.0.19,local_lock=none,addr=10.23.0.35
# Example from SITE 2, hana-s2-db1
sapnfsafs.file.core.windows.net:/sapnfsafs/hn1-shared-s2
 Flags: rw,relatime,vers=4.1,rsize=1048576,wsize=1048576,namlen=255,hard,proto=tcp,timeo=600,retrans=2,sec=sys,clientaddr=10.23.0.22,local_lock=none,addr=10.23.0.35

Prepare the data and log local file systems

In the presented configuration, file systems /hana/data and /hana/log are deployed on managed disk and are locally attached to each HANA DB VM. You'll need to execute the steps to create the local data and log volumes on each HANA DB virtual machine.

Set up the disk layout with Logical Volume Manager (LVM). The following example assumes that each HANA virtual machine has three data disks attached, that are used to create two volumes.

  1. [AH] List all of the available disks:

    ls /dev/disk/azure/scsi1/lun*

    Example output:

    /dev/disk/azure/scsi1/lun0  /dev/disk/azure/scsi1/lun1  /dev/disk/azure/scsi1/lun2

  2. [AH] Create physical volumes for all of the disks that you want to use:

    sudo pvcreate /dev/disk/azure/scsi1/lun0
sudo pvcreate /dev/disk/azure/scsi1/lun1
sudo pvcreate /dev/disk/azure/scsi1/lun2

  3. [AH] Create a volume group for the data files. Use one volume group for the log files and one for the shared directory of SAP HANA:\

    sudo vgcreate vg_hana_data_HN1 /dev/disk/azure/scsi1/lun0 /dev/disk/azure/scsi1/lun1
sudo vgcreate vg_hana_log_HN1 /dev/disk/azure/scsi1/lun2

  4. [AH] Create the logical volumes.

    A linear volume is created when you use lvcreate without the -i switch. We suggest that you create a striped volume for better I/O performance, and align the stripe sizes to the values documented in SAP HANA VM storage configurations. The -i argument should be the number of the underlying physical volumes and the -I argument is the stripe size. In this document, two physical volumes are used for the data volume, so the -i switch argument is set to 2. The stripe size for the data volume is 256 KiB. One physical volume is used for the log volume, so no -i or -I switches are explicitly used for the log volume commands.

    Important

    Use the -i switch and set it to the number of the underlying physical volume when you use more than one physical volume for each data or log volumes. Use the -I switch to specify the stripe size, when creating a striped volume.
    See SAP HANA VM storage configurations for recommended storage configurations, including stripe sizes and number of disks.

    sudo lvcreate -i 2 -I 256 -l 100%FREE -n hana_data vg_hana_data_HN1
sudo lvcreate -l 100%FREE -n hana_log vg_hana_log_HN1
sudo mkfs.xfs /dev/vg_hana_data_HN1/hana_data
sudo mkfs.xfs /dev/vg_hana_log_HN1/hana_log

  5. [AH] Create the mount directories and copy the UUID of all of the logical volumes:

    sudo mkdir -p /hana/data/HN1
sudo mkdir -p /hana/log/HN1
# Write down the ID of /dev/vg_hana_data_HN1/hana_data and /dev/vg_hana_log_HN1/hana_log
sudo blkid

  6. [AH] Create fstab entries for the logical volumes and mount:

    sudo vi /etc/fstab

    Insert the following line in the /etc/fstab file:

    /dev/disk/by-uuid/UUID of /dev/mapper/vg_hana_data_HN1-hana_data /hana/data/HN1 xfs  defaults,nofail  0  2
/dev/disk/by-uuid/UUID of /dev/mapper/vg_hana_log_HN1-hana_log /hana/log/HN1 xfs  defaults,nofail  0  2

    Mount the new volumes:

    sudo mount -a

Create a Pacemaker cluster

Follow the steps in Setting up Pacemaker on SUSE Linux Enterprise Server in Azure to create a basic Pacemaker cluster for this HANA server. Include all virtual machines, including the majority maker in the cluster.

Important

Don't set quorum expected-votes to 2, as this is not a two node cluster.
Make sure that cluster property concurrent-fencing is enabled, so that node fencing is deserialized.

Installation

In this example for deploying SAP HANA in scale-out configuration with HSR on Azure VMs, we've used HANA 2.0 SP5.

Prepare for HANA installation

  1. [AH] Before the HANA installation, set the root password. You can disable the root password after the installation has been completed. Execute as root command passwd.

  2. [1,2] Change the permissions on /hana/shared

    chmod 775 /hana/shared

  3. [1] Verify that you can log in via SSH to the HANA DB VMs in this site hana-s1-db2 and hana-s1-db3, without being prompted for a password. If that isn't the case, exchange ssh keys as described in Enable SSH Access via Public Key.

    ssh root@hana-s1-db2
ssh root@hana-s1-db3

  4. [2] Verify that you can log in via SSH to the HANA DB VMs in this site hana-s2-db2 and hana-s2-db3, without being prompted for a password.
    If that isn't the case, exchange ssh keys.

    ssh root@hana-s2-db2
ssh root@hana-s2-db3

  5. [AH] Install additional packages, which are required for HANA 2.0 SP4 and above. For more information, see SAP Note 2593824 for your SLES version.

    # In this example, using SLES12 SP5
sudo zypper install libgcc_s1 libstdc++6 libatomic1

HANA installation on the first node on each site

  1. [1] Install SAP HANA by following the instructions in the SAP HANA 2.0 Installation and Update guide. In the instructions that follow, we show the SAP HANA installation on the first node on SITE 1.

    a. Start the hdblcm program as root from the HANA installation software directory. Use the internal_network parameter and pass the address space for subnet, which is used for the internal HANA inter-node communication.

    ./hdblcm --internal_network=10.23.1.128/26

    b. At the prompt, enter the following values:

    • For Choose an action: enter 1 (for install)
    • For Additional components for installation: enter 2, 3
    • For installation path: press Enter (defaults to /hana/shared)
    • For Local Host Name: press Enter to accept the default
    • For Do you want to add hosts to the system?: enter n
    • For SAP HANA System ID: enter HN1
    • For Instance number [00]: enter 03
    • For Local Host Worker Group [default]: press Enter to accept the default
    • For Select System Usage / Enter index [4]: enter 4 (for custom)
    • For Location of Data Volumes [/hana/data/HN1]: press Enter to accept the default
    • For Location of Log Volumes [/hana/log/HN1]: press Enter to accept the default
    • For Restrict maximum memory allocation? [n]: enter n
    • For Certificate Host Name For Host hana-s1-db1 [hana-s1-db1]: press Enter to accept the default
    • For SAP Host Agent User (sapadm) Password: enter the password
    • For Confirm SAP Host Agent User (sapadm) Password: enter the password
    • For System Administrator (hn1adm) Password: enter the password
    • For System Administrator Home Directory [/usr/sap/HN1/home]: press Enter to accept the default
    • For System Administrator Login Shell [/bin/sh]: press Enter to accept the default
    • For System Administrator User ID [1001]: press Enter to accept the default
    • For Enter ID of User Group (sapsys) [79]: press Enter to accept the default
    • For System Database User (system) Password: enter the system's password
    • For Confirm System Database User (system) Password: enter system's password
    • For Restart system after machine reboot? [n]: enter n
    • For Do you want to continue (y/n): validate the summary and if everything looks good, enter y

  2. [2] Repeat the preceding step to install SAP HANA on the first node on SITE 2.

  3. [1,2] Verify global.ini

    Display global.ini, and ensure that the configuration for the internal SAP HANA inter-node communication is in place. Verify the communication section. It should have the address space for the inter subnet, and listeninterface should be set to .internal. Verify the internal_hostname_resolution section. It should have the IP addresses for the HANA virtual machines that belong to the inter subnet.

      sudo cat /usr/sap/HN1/SYS/global/hdb/custom/config/global.ini
  # Example from SITE1 
  [communication]
  internal_network = 10.23.1.128/26
  listeninterface = .internal
  [internal_hostname_resolution]
  10.23.1.132 = hana-s1-db1
  10.23.1.133 = hana-s1-db2
  10.23.1.134 = hana-s1-db3

  4. [1,2] Prepare global.ini for installation in non-shared environment, as described in SAP note 2080991.

     sudo vi /usr/sap/HN1/SYS/global/hdb/custom/config/global.ini
 [persistence]
 basepath_shared = no

  5. [1,2] Restart SAP HANA to activate the changes.

     sudo -u hn1adm /usr/sap/hostctrl/exe/sapcontrol -nr 03 -function StopSystem
 sudo -u hn1adm /usr/sap/hostctrl/exe/sapcontrol -nr 03 -function StartSystem

  6. [1,2] Verify that the client interface will be using the IP addresses from the client subnet for communication.

    # Execute as hn1adm
/usr/sap/HN1/HDB03/exe/hdbsql -u SYSTEM -p "password" -i 03 -d SYSTEMDB 'select * from SYS.M_HOST_INFORMATION'|grep net_publicname
# Expected result - example from SITE 2
"hana-s2-db1","net_publicname","10.23.0.22"

    For information about how to verify the configuration, see SAP Note 2183363 - Configuration of SAP HANA internal network.

  7. [AH] Change permissions on the data and log directories to avoid HANA installation error.

     sudo chmod o+w -R /hana/data /hana/log

  8. [1] Install the secondary HANA nodes. The example instructions in this step are for SITE 1.

    a. Start the resident hdblcm program as root.

     cd /hana/shared/HN1/hdblcm
 ./hdblcm

    b. At the prompt, enter the following values:

    • For Choose an action: enter 2 (for add hosts)
    • For Enter comma separated host names to add: hana-s1-db2, hana-s1-db3
    • For Additional components for installation: enter 2, 3
    • For Enter Root User Name [root]: press Enter to accept the default
    • For Select roles for host 'hana-s1-db2' [1]: 1 (for worker)
    • For Enter Host Failover Group for host 'hana-s1-db2' [default]: press Enter to accept the default
    • For Enter Storage Partition Number for host 'hana-s1-db2' [<<assign automatically>>]: press Enter to accept the default
    • For Enter Worker Group for host 'hana-s1-db2' [default]: press Enter to accept the default
    • For Select roles for host 'hana-s1-db3' [1]: 1 (for worker)
    • For Enter Host Failover Group for host 'hana-s1-db3' [default]: press Enter to accept the default
    • For Enter Storage Partition Number for host 'hana-s1-db3' [<<assign automatically>>]: press Enter to accept the default
    • For Enter Worker Group for host 'hana-s1-db3' [default]: press Enter to accept the default
    • For System Administrator (hn1adm) Password: enter the password
    • For Enter SAP Host Agent User (sapadm) Password: enter the password
    • For Confirm SAP Host Agent User (sapadm) Password: enter the password
    • For Certificate Host Name For Host hana-s1-db2 [hana-s1-db2]: press Enter to accept the default
    • For Certificate Host Name For Host hana-s1-db3 [hana-s1-db3]: press Enter to accept the default
    • For Do you want to continue (y/n): validate the summary and if everything looks good, enter y

  9. [2] Repeat the preceding step to install the secondary SAP HANA nodes on SITE 2.

Configure SAP HANA 2.0 System Replication

  1. [1] Configure System Replication on SITE 1:

    Back up the databases as hn1adm:

    hdbsql -d SYSTEMDB -u SYSTEM -p "passwd" -i 03 "BACKUP DATA USING FILE ('initialbackupSYS')"
hdbsql -d HN1 -u SYSTEM -p "passwd" -i 03 "BACKUP DATA USING FILE ('initialbackupHN1')"

    Copy the system PKI files to the secondary site:

    scp /usr/sap/HN1/SYS/global/security/rsecssfs/data/SSFS_HN1.DAT hana-s2-db1:/usr/sap/HN1/SYS/global/security/rsecssfs/data/
scp /usr/sap/HN1/SYS/global/security/rsecssfs/key/SSFS_HN1.KEY  hana-s2-db1:/usr/sap/HN1/SYS/global/security/rsecssfs/key/

    Create the primary site:

    hdbnsutil -sr_enable --name=HANA_S1

  2. [2] Configure System Replication on SITE 2:

    Register the second site to start the system replication. Run the following command as <hanasid>adm:

    sapcontrol -nr 03 -function StopWait 600 10
hdbnsutil -sr_register --remoteHost=hana-s1-db1 --remoteInstance=03 --replicationMode=sync --name=HANA_S2
sapcontrol -nr 03 -function StartSystem

  3. [1] Check replication status

    Check the replication status and wait until all databases are in sync.

    sudo su - hn1adm -c "python /usr/sap/HN1/HDB03/exe/python_support/systemReplicationStatus.py"

# | Database | Host          | Port  | Service Name | Volume ID | Site ID | Site Name | Secondary     | Secondary | Secondary | Secondary | Secondary     | Replication | Replication | Replication    |
# |          |               |       |              |           |         |           | Host          | Port      | Site ID   | Site Name | Active Status | Mode        | Status      | Status Details |
# | -------- | ------------- | ----- | ------------ | --------- | ------- | --------- | ------------- | --------- | --------- | --------- | ------------- | ----------- | ----------- | -------------- |
# | HN1      | hana-s1-db3   | 30303 | indexserver  |         5 |       1 | HANA_S1   | hana-s2-db3   |     30303 |         2 | HANA_S2   | YES           | SYNC        | ACTIVE      |                |
# | SYSTEMDB | hana-s1-db1   | 30301 | nameserver   |         1 |       1 | HANA_S1   | hana-s2-db1   |     30301 |         2 | HANA_S2   | YES           | SYNC        | ACTIVE      |                |
# | HN1      | hana-s1-db1   | 30307 | xsengine     |         2 |       1 | HANA_S1   | hana-s2-db1   |     30307 |         2 | HANA_S2   | YES           | SYNC        | ACTIVE      |                |
# | HN1      | hana-s1-db1   | 30303 | indexserver  |         3 |       1 | HANA_S1   | hana-s2-db1   |     30303 |         2 | HANA_S2   | YES           | SYNC        | ACTIVE      |                |
# | HN1      | hana-s1-db2   | 30303 | indexserver  |         4 |       1 | HANA_S1   | hana-s2-db2   |     30303 |         2 | HANA_S2   | YES           | SYNC        | ACTIVE      |                |
#
# status system replication site "2": ACTIVE
# overall system replication status: ACTIVE
#
# Local System Replication State
#
# mode: PRIMARY
# site id: 1
# site name: HANA_S1

  4. [1,2] Change the HANA configuration so that communication for HANA system replication is directed through the HANA system replication virtual network interfaces.

    • Stop HANA on both sites

      sudo -u hn1adm /usr/sap/hostctrl/exe/sapcontrol -nr 03 -function StopSystem HDB

    • Edit global.ini to add the host mapping for HANA system replication: use the IP addresses from the hsr subnet.

      sudo vi /usr/sap/HN1/SYS/global/hdb/custom/config/global.ini
#Add the section
[system_replication_hostname_resolution]
10.23.1.196 = hana-s1-db1
10.23.1.197 = hana-s1-db2
10.23.1.198 = hana-s1-db3
10.23.1.199 = hana-s2-db1
10.23.1.200 = hana-s2-db2
10.23.1.201 = hana-s2-db3

    • Start HANA on both sites

      sudo -u hn1adm /usr/sap/hostctrl/exe/sapcontrol -nr 03 -function StartSystem HDB

    For more information, see Host Name resolution for System Replication.

Create file system resources

Create a dummy file system cluster resource, which will monitor and report failures, in case there's a problem accessing the NFS-mounted file system /hana/shared. That allows the cluster to trigger failover, in case there's a problem accessing /hana/shared. For more information, see Handling failed NFS share in SUSE HA cluster for HANA system replication

  1. [1] Place pacemaker in maintenance mode, in preparation for the creation of the HANA cluster resources.

    crm configure property maintenance-mode=true

  2. [1,2] Create the directory on the NFS mounted file system /hana/shared, which will be used in the special file system monitoring resource. The directories need to be created on both sites.

    mkdir -p /hana/shared/HN1/check

  3. [AH] Create the directory, which will be used to mount the special file system monitoring resource. The directory needs to be created on all HANA cluster nodes.

    mkdir -p /hana/check

  4. [1] Create the file system cluster resources.

    crm configure primitive fs_HN1_HDB03_fscheck Filesystem \
  params device="/hana/shared/HN1/check" \
  directory="/hana/check" fstype=nfs4 \
  options="bind,defaults,rw,hard,proto=tcp,noatime,nfsvers=4.1,lock" \
  op monitor interval=120 timeout=120 on-fail=fence \
  op_params OCF_CHECK_LEVEL=20 \
  op start interval=0 timeout=120 op stop interval=0 timeout=120

crm configure clone cln_fs_HN1_HDB03_fscheck fs_HN1_HDB03_fscheck \
  meta clone-node-max=1 interleave=true

crm configure location loc_cln_fs_HN1_HDB03_fscheck_not_on_mm \
  cln_fs_HN1_HDB03_fscheck -inf: hana-s-mm

    OCF_CHECK_LEVEL=20 attribute is added to the monitor operation, so that monitor operations perform a read/write test on the file system. Without this attribute, the monitor operation only verifies that the file system is mounted. This can be a problem because when connectivity is lost, the file system may remain mounted, despite being inaccessible.

    on-fail=fence attribute is also added to the monitor operation. With this option, if the monitor operation fails on a node, that node is immediately fenced.

Implement HANA HA hooks SAPHanaSrMultiTarget and susChkSrv

This important step is to optimize the integration with the cluster and detection when a cluster failover is possible. It's highly recommended to configure SAPHanaSrMultiTarget Python hook. For HANA 2.0 SP5 and higher, implementing both SAPHanaSrMultiTarget and susChkSrv hooks is recommended.

Note

SAPHanaSrMultiTarget HA provider replaces SAPHanaSR for HANA scale-out. SAPHanaSR was described in earlier version of this document.
See SUSE blog post about changes with the new HANA HA hook.

Provided steps for SAPHanaSrMultiTarget hook are for a new installation. Upgrading an existing environment from SAPHanaSR to SAPHanaSrMultiTarget provider requires several changes and are NOT described in this document. If the existing environment uses no third site for disaster recovery and HANA multi-target system replication isn't used, SAPHanaSR HA provider can remain in use.

SusChkSrv extends the functionality of the main SAPHanaSrMultiTarget HA provider. It acts in the situation when HANA process hdbindexserver crashes. If a single process crashes typically HANA tries to restart it. Restarting the indexserver process can take a long time, during which the HANA database isn't responsive. With susChkSrv implemented, an immediate and configurable action is executed, instead of waiting on hdbindexserver process to restart on the same node. In HANA scale-out susChkSrv acts for every HANA VM independently. The configured action will kill HANA or fence the affected VM, which triggers a failover in the configured timeout period.

SUSE SLES 15 SP1 or higher is required for operation of both HANA HA hooks. Following table shows other dependencies.

SAP HANA HA hook HANA version required SAPHanaSR-ScaleOut required
SAPHanaSrMultiTarget HANA 2.0 SPS4 or higher 0.180 or higher
susChkSrv HANA 2.0 SPS5 or higher 0.184.1 or higher

Steps to implement both hooks:

  1. [1,2] Stop HANA on both system replication sites. Execute as <sid>adm:

    sapcontrol -nr 03 -function StopSystem

  2. [1,2] Adjust global.ini on each cluster site. If the prerequisites for susChkSrv hook aren't met, entire block [ha_dr_provider_suschksrv] shouldn't be configured.
    You can adjust the behavior of susChkSrv with parameter action_on_lost. Valid values are [ ignore | stop | kill | fence ].

    # add to global.ini on both sites. Do not copy global.ini between sites.
[ha_dr_provider_saphanasrmultitarget]
provider = SAPHanaSrMultiTarget
path = /usr/share/SAPHanaSR-ScaleOut
execution_order = 1

[ha_dr_provider_suschksrv]
provider = susChkSrv
path = /usr/share/SAPHanaSR-ScaleOut
execution_order = 3
action_on_lost = kill

[trace]
ha_dr_saphanasrmultitarget = info

    Default location of the HA hooks as delivered by SUSE is /usr/share/SAPHanaSR-ScaleOut. Using the standard location brings a benefit, that the python hook code is automatically updated through OS or package updates and gets used by HANA at next restart. With an optional own path, such as /hana/shared/myHooks you can decouple OS updates from the used hook version.

  3. [AH] The cluster requires sudoers configuration on the cluster nodes for <sid>adm. In this example that is achieved by creating a new file. Execute the commands as root adapt the values of hn1 with correct lowercase SID.

    cat << EOF > /etc/sudoers.d/20-saphana
# SAPHanaSR-ScaleOut needs for HA/DR hook scripts
so1adm ALL=(ALL) NOPASSWD: /usr/sbin/crm_attribute -n hana_hn1_site_srHook_*
so1adm ALL=(ALL) NOPASSWD: /usr/sbin/crm_attribute -n hana_hn1_gsh *
so1adm ALL=(ALL) NOPASSWD: /usr/sbin/SAPHanaSR-hookHelper --sid=hn1 *
EOF

  4. [1,2] Start SAP HANA on both replication sites. Execute as <sid>adm.

    sapcontrol -nr 03 -function StartSystem

  5. [A] Verify the hook installation is active on all cluster nodes. Execute as <sid>adm.

    cdtrace
grep HADR.*load.*SAPHanaSrMultiTarget nameserver_*.trc | tail -3
# Example output
# nameserver_hana-s1-db1.31001.000.trc:[14162]{-1}[-1/-1] 2023-01-26 12:53:55.728027 i ha_dr_provider   HADRProviderManager.cpp(00083) : loading HA/DR Provider 'SAPHanaSrMultiTarget' from /usr/share/SAPHanaSR-ScaleOut/
grep SAPHanaSr.*init nameserver_*.trc | tail -3
# Example output
# nameserver_hana-s1-db1.31001.000.trc:[17636]{-1}[-1/-1] 2023-01-26 16:30:19.256705 i ha_dr_SAPHanaSrM SAPHanaSrMultiTarget.py(00080) : SAPHanaSrMultiTarget.init() CALLING CRM: <sudo /usr/sbin/crm_attribute -n hana_hn1_gsh -v 2.2  -l reboot> rc=0
# nameserver_hana-s1-db1.31001.000.trc:[17636]{-1}[-1/-1] 2023-01-26 16:30:19.256739 i ha_dr_SAPHanaSrM SAPHanaSrMultiTarget.py(00081) : SAPHanaSrMultiTarget.init() Running srHookGeneration 2.2, see attribute hana_hn1_gsh too

    Verify the susChkSrv hook installation. Execute as <sid>adm.

    cdtrace
egrep '(LOST:|STOP:|START:|DOWN:|init|load|fail)' nameserver_suschksrv.trc
# Example output
# 2023-01-19 08:23:10.581529  [1674116590-10005] susChkSrv.init() version 0.7.7, parameter info: action_on_lost=fence stop_timeout=20 kill_signal=9
# 2023-01-19 08:23:31.553566  [1674116611-14022] START: indexserver event looks like graceful tenant start
# 2023-01-19 08:23:52.834813  [1674116632-15235] START: indexserver event looks like graceful tenant start (indexserver started)

Create SAP HANA cluster resources

  1. [1] Create the HANA cluster resources. Execute the following commands as root.

    1. Make sure the cluster is already maintenance mode.

    2. Next, create the HANA Topology resource.

      sudo crm configure primitive rsc_SAPHanaTopology_HN1_HDB03 ocf:suse:SAPHanaTopology \
  op monitor interval="10" timeout="600" \
  op start interval="0" timeout="600" \
  op stop interval="0" timeout="300" \
  params SID="HN1" InstanceNumber="03"

sudo crm configure clone cln_SAPHanaTopology_HN1_HDB03 rsc_SAPHanaTopology_HN1_HDB03 \
 meta clone-node-max="1" target-role="Started" interleave="true"

    3. Next, create the HANA instance resource.

      Note

      This article contains references to terms that Microsoft no longer uses. When these terms are removed from the software, we'll remove them from this article.

      sudo crm configure primitive rsc_SAPHana_HN1_HDB03 ocf:suse:SAPHanaController \
  op start interval="0" timeout="3600" \
  op stop interval="0" timeout="3600" \
  op promote interval="0" timeout="3600" \
  op monitor interval="60" role="Master" timeout="700" \
  op monitor interval="61" role="Slave" timeout="700" \
  params SID="HN1" InstanceNumber="03" PREFER_SITE_TAKEOVER="true" \
  DUPLICATE_PRIMARY_TIMEOUT="7200" AUTOMATED_REGISTER="false"

sudo crm configure ms msl_SAPHana_HN1_HDB03 rsc_SAPHana_HN1_HDB03 \
  meta clone-node-max="1" master-max="1" interleave="true"

      Important

      We recommend as a best practice that you only set AUTOMATED_REGISTER to no, while performing thorough fail-over tests, to prevent failed primary instance to automatically register as secondary. Once the fail-over tests have completed successfully, set AUTOMATED_REGISTER to yes, so that after takeover system replication can resume automatically.

    4. Create Virtual IP and associated resources.

      sudo crm configure primitive rsc_ip_HN1_HDB03 ocf:heartbeat:IPaddr2 \
  op monitor interval="10s" timeout="20s" \
  params ip="10.23.0.27"

sudo crm configure primitive rsc_nc_HN1_HDB03 azure-lb port=62503 \
  op monitor timeout=20s interval=10 \
  meta resource-stickiness=0

sudo crm configure group g_ip_HN1_HDB03 rsc_ip_HN1_HDB03 rsc_nc_HN1_HDB03

    5. Create the cluster constraints

      # Colocate the IP with HANA master
sudo crm configure colocation col_saphana_ip_HN1_HDB03 4000: g_ip_HN1_HDB03:Started \
  msl_SAPHana_HN1_HDB03:Master  

# Start HANA Topology before HANA  instance
sudo crm configure order ord_SAPHana_HN1_HDB03 Optional: cln_SAPHanaTopology_HN1_HDB03 \
  msl_SAPHana_HN1_HDB03

# HANA resources don't run on the majority maker node
sudo crm configure location loc_SAPHanaCon_not_on_majority_maker msl_SAPHana_HN1_HDB03 -inf: hana-s-mm
sudo crm configure location loc_SAPHanaTop_not_on_majority_maker cln_SAPHanaTopology_HN1_HDB03 -inf: hana-s-mm

  2. [1] Configure additional cluster properties

    sudo crm configure rsc_defaults resource-stickiness=1000
sudo crm configure rsc_defaults migration-threshold=50

  3. [1] Place the cluster out of maintenance mode. Make sure that the cluster status is ok and that all of the resources are started.

    # Cleanup any failed resources - the following command is example 
crm resource cleanup rsc_SAPHana_HN1_HDB03

# Place the cluster out of maintenance mode
sudo crm configure property maintenance-mode=false

  4. [1] Verify the communication between the HANA HA hook and the cluster, showing status SOK for SID and both replication sites with status P(rimary) or S(econdary).

    sudo /usr/sbin/SAPHanaSR-showAttr
# Expected result
# Global cib-time                 maintenance prim  sec sync_state upd
# ---------------------------------------------------------------------
# HN1    Fri Jan 27 10:38:46 2023 false       HANA_S1 -   SOK        ok
# 
# Sites     lpt        lss mns        srHook srr
# -----------------------------------------------
# HANA_S1     1674815869 4   hana-s1-db1 PRIM   P
# HANA_S2     30         4   hana-s2-db1 SWAIT  S

    Note

    The timeouts in the above configuration are just examples and may need to be adapted to the specific HANA setup. For instance, you may need to increase the start timeout, if it takes longer to start the SAP HANA database.

Test SAP HANA failover

Note

This article contains references to terms that Microsoft no longer uses. When these terms are removed from the software, we’ll remove them from this article.

  1. Before you start a test, check the cluster and SAP HANA system replication status.

    a. Verify that there are no failed cluster actions

    #Verify that there are no failed cluster actions
crm status
# Example 
#7 nodes configured
#24 resource instances configured
#
#Online: [ hana-s-mm hana-s1-db1 hana-s1-db2 hana-s1-db3 hana-s2-db1 hana-s2-db2 hana-s2-db3 ]
#
#Full list of resources:
#
# stonith-sbd    (stonith:external/sbd): Started hana-s-mm
# Clone Set: cln_fs_HN1_HDB03_fscheck [fs_HN1_HDB03_fscheck]
#     Started: [ hana-s1-db1 hana-s1-db2 hana-s1-db3 hana-s2-db1 hana-s2-db2 hana-s2-db3 ]
#     Stopped: [ hana-s-mm ]
# Clone Set: cln_SAPHanaTopology_HN1_HDB03 [rsc_SAPHanaTopology_HN1_HDB03]
#     Started: [ hana-s1-db1 hana-s1-db2 hana-s1-db3 hana-s2-db1 hana-s2-db2 hana-s2-db3 ]
#     Stopped: [ hana-s-mm ]
# Master/Slave Set: msl_SAPHana_HN1_HDB03 [rsc_SAPHana_HN1_HDB03]
#     Masters: [ hana-s1-db1 ]
#     Slaves: [ hana-s1-db2 hana-s1-db3 hana-s2-db1 hana-s2-db2 hana-s2-db3 ]
#     Stopped: [ hana-s-mm ]
# Resource Group: g_ip_HN1_HDB03
#     rsc_ip_HN1_HDB03   (ocf::heartbeat:IPaddr2):       Started hana-s1-db1
#     rsc_nc_HN1_HDB03   (ocf::heartbeat:azure-lb):      Started hana-s1-db1

    b. Verify that SAP HANA system replication is in sync

    # Verify HANA HSR is in sync
sudo su - hn1adm -c "python /usr/sap/HN1/HDB03/exe/python_support/systemReplicationStatus.py"
#| Database | Host         | Port  | Service Name | Volume ID | Site ID | Site Name | Secondary    | Secondary | Secondary | Secondary | Secondary     | Replication | Replication | Replication    |
#|          |              |       |              |           |         |           | Host         | Port      | Site ID   | Site Name | Active Status | Mode        | Status      | Status Details |
#| -------- | ------------ | ----- | ------------ | --------- | ------- | --------- | ------------ | --------- | --------- | --------- | ------------- | ----------- | ----------- | -------------- |
#| SYSTEMDB | hana-s1-db1  | 30301 | nameserver   |         1 |       1 | HANA_S1   | hana-s2-db1  |     30301 |         2 | HANA_S2   | YES           | SYNC        | ACTIVE      |                |
#| HN1      | hana-s1-db1  | 30307 | xsengine     |         2 |       1 | HANA_S1   | hana-s2-db1  |     30307 |         2 | HANA_S2   | YES           | SYNC        | ACTIVE      |                |
#| HN1      | hana-s1-db1  | 30303 | indexserver  |         3 |       1 | HANA_S1   | hana-s2-db1  |     30303 |         2 | HANA_S2   | YES           | SYNC        | ACTIVE      |                |
#| HN1      | hana-s1-db3  | 30303 | indexserver  |         4 |       1 | HANA_S1   | hana-s2-db3  |     30303 |         2 | HANA_S2   | YES           | SYNC        | ACTIVE      |                |
#| HN1      | hana-s1-db2  | 30303 | indexserver  |         5 |       1 | HANA_S1   | hana-s2-db2  |     30303 |         2 | HANA_S2   | YES           | SYNC        | ACTIVE      |                |
#
#status system replication site "1": ACTIVE
#overall system replication status: ACTIVE
#
#Local System Replication State
#~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
#
#mode: PRIMARY
#site id: 1
#site name: HANA_S1

  2. We recommend to thoroughly validate the SAP HANA cluster configuration, by performing the tests, documented in HA for SAP HANA on Azure VMs on SLES and in SLES Replication scale-out Performance Optimized Scenario.

  3. Verify the cluster configuration for a failure scenario, when a node loses access to the NFS share (/hana/shared).

    The SAP HANA resource agents depend on binaries, stored on /hana/shared to perform operations during failover. File system /hana/shared is mounted over NFS in the presented configuration. A test that can be performed, is to create a temporary firewall rule to block access to the /hana/shared NFS mounted file system on one of the primary site VMs. This approach validates that the cluster will fail over, if access to /hana/shared is lost on the active system replication site.

    Expected result: When you block the access to the /hana/shared NFS mounted file system on one of the primary site VMs, the monitoring operation that performs read/write operation on file system, will fail, as it is not able to access the file system and will trigger HANA resource failover. The same result is expected when your HANA node loses access to the NFS share.

    You can check the state of the cluster resources by executing crm_mon or crm status. Resource state before starting the test:

    # Output of crm_mon
#7 nodes configured
#24 resource instances configured
#
#Online: [ hana-s-mm hana-s1-db1 hana-s1-db2 hana-s1-db3 hana-s2-db1 hana-s2-db2 hana-s2-db3 ]
#
#Active resources:
#
#stonith-sbd     (stonith:external/sbd): Started hana-s-mm
# Clone Set: cln_fs_HN1_HDB03_fscheck [fs_HN1_HDB03_fscheck]
#     Started: [ hana-s1-db1 hana-s1-db2 hana-s1-db3 hana-s2-db1 hana-s2-db2 hana-s2-db3 ]
# Clone Set: cln_SAPHanaTopology_HN1_HDB03 [rsc_SAPHanaTopology_HN1_HDB03]
#     Started: [ hana-s1-db1 hana-s1-db2 hana-s1-db3 hana-s2-db1 hana-s2-db2 hana-s2-db3 ]
# Master/Slave Set: msl_SAPHana_HN1_HDB03 [rsc_SAPHana_HN1_HDB03]
#     Masters: [ hana-s1-db1 ]
#     Slaves: [ hana-s1-db2 hana-s1-db3 hana-s2-db1 hana-s2-db2 hana-s2-db3 ]
# Resource Group: g_ip_HN1_HDB03
#     rsc_ip_HN1_HDB03   (ocf::heartbeat:IPaddr2):       Started hana-s2-db1
#     rsc_nc_HN1_HDB03   (ocf::heartbeat:azure-lb):      Started hana-s2-db1

    To simulate failure for /hana/shared:

    • If using NFS on Azure NetApp Files, first confirm the IP address for the /hana/shared Azure NetApp Files volume on the primary site. You can do that by running df -kh|grep /hana/shared.
    • If using NFS on Azure Files, first determine the IP address of the private end point for your storage account.

    Then, set up a temporary firewall rule to block access to the IP address of the /hana/shared NFS file system by executing the following command on one of the primary HANA system replication site VMs.

    In this example, the command was executed on hana-s1-db1 for Azure NetApp Files volume /hana/shared.

    iptables -A INPUT -s 10.23.1.7 -j DROP; iptables -A OUTPUT -d 10.23.1.7 -j DROP

    The cluster resources will be migrated to the other HANA system replication site.

    If you set AUTOMATED_REGISTER="false", you'll need to configure SAP HANA system replication on secondary site. In this case, you can execute these commands to reconfigure SAP HANA as secondary.

    # Execute on the secondary 
su - hn1adm
# Make sure HANA is not running on the secondary site. If it is started, stop HANA
sapcontrol -nr 03 -function StopWait 600 10
# Register the HANA secondary site
hdbnsutil -sr_register --name=HANA_S1 --remoteHost=hana-s2-db1 --remoteInstance=03 --replicationMode=sync
# Switch back to root and cleanup failed resources
crm resource cleanup SAPHana_HN1_HDB03

    The state of the resources, after the test:

    # Output of crm_mon
#7 nodes configured
#24 resource instances configured
#
#Online: [ hana-s-mm hana-s1-db1 hana-s1-db2 hana-s1-db3 hana-s2-db1 hana-s2-db2 hana-s2-db3 ]
#
#Active resources:
#
#stonith-sbd     (stonith:external/sbd): Started hana-s-mm
# Clone Set: cln_fs_HN1_HDB03_fscheck [fs_HN1_HDB03_fscheck]
#     Started: [ hana-s1-db1 hana-s1-db2 hana-s1-db3 hana-s2-db1 hana-s2-db2 hana-s2-db3 ]
# Clone Set: cln_SAPHanaTopology_HN1_HDB03 [rsc_SAPHanaTopology_HN1_HDB03]
#     Started: [ hana-s1-db1 hana-s1-db2 hana-s1-db3 hana-s2-db1 hana-s2-db2 hana-s2-db3 ]
# Master/Slave Set: msl_SAPHana_HN1_HDB03 [rsc_SAPHana_HN1_HDB03]
#     Masters: [ hana-s2-db1 ]
#     Slaves: [ hana-s1-db1 hana-s1-db2 hana-s1-db3 hana-s2-db2 hana-s2-db3 ]
# Resource Group: g_ip_HN1_HDB03
#     rsc_ip_HN1_HDB03   (ocf::heartbeat:IPaddr2):       Started hana-s2-db1
#     rsc_nc_HN1_HDB03   (ocf::heartbeat:azure-lb):      Started hana-s2-db1

Next steps