Azure – Create ASCS and ERS Internal Load Balancer

In Microsoft Azure, a TCP Internal Load Balancer is used to facilitate failover of the ASCS and ERS virtual IP’s. The load balancer consists of two frontends, each assigned an IP address from the subnet that it operates in. In this example, we will be using the following IP addresses for the load balancer frontends corresponding to each virtual host:

Following the steps provided in Azure – Using an Internal Load Balancer and Responding to Load Balancer Health Checks, create and configure the following Azure and LifeKeeper resources.

1. Create a single Load Balancer in Azure, ilb-sps-ascs-ers, with the following properties.

Once created, the Load Balancing Services → Load Balancer page in the Microsoft Azure Console will show the newly created load balancer.

2. Following the steps in Responding to Load Balancer Health Checks, create two LifeKeeper LB Health Check resources, ilb-sps-ascs and ilb-sps-ers, with the following properties. Notice that ilb-sps-ascs is created on node-a and extended to node-b, while ilb-sps-ers is created on node-b and extended to node-a. The icon indicates that the default option is chosen.

Field	Value
Create Resource Wizard
Switchback Type	intelligent
Server	node-a
Reply daemon Port	51098
Reply daemon message	None (Empty)
LB Health Check Resource Tag	ilb-sps-ascs
Pre-Extend Wizard
Target Server	node-b
Switchback Type	intelligent
Template Priority	1
Target Priority	10
Extend LB Health Check Resource Hierarchy Wizard
LB Health Check Resource Tag	ilb-sps-ascs

Field	Value
Create Resource Wizard
Switchback Type	intelligent
Server	node-b
Reply daemon Port	52098
Reply daemon message	None (Empty)
LB Health Check Resource Tag	ilb-sps-ers
Pre-Extend Wizard
Target Server	node-a
Switchback Type	intelligent
Template Priority	1
Target Priority	10
Extend LB Health Check Resource Hierarchy Wizard
LB Health Check Resource Tag	ilb-sps-ers

The resources will appear in the LifeKeeper GUI resource pane once they have been created and extended successfully.

3. Following the steps described in Creating an IP Resource, use the following parameters to create and extend a LifeKeeper IP resource (ip-sps-ascs) to protect the ASCS virtual IP address on node-a and node-b. Notice that the IP resource is being created on node-a and extended to node-b. Also note that the resulting resource should not be extended to node-c, the witness node. The icon indicates that the default option is chosen.

Field	Value
Create Resource Wizard
Switchback Type	intelligent
Server	node-a
IP Resource	10.20.0.10
Netmask	255.255.252.0
Network Interface	eth0
IP Resource Tag	ip-sps-ascs
Pre-Extend Wizard
Target Server	node-b
Switchback Type	intelligent
Template Priority	1
Target Priority	10
Extend comm/ip Resource Hierarchy Wizard
IP Resource	10.20.0.10
Netmask	255.255.252.0
Network Interface	eth0
IP Resource Tag	ip-sps-ascs

4. Following the steps described in Creating an IP Resource, use the following parameters to create and extend a LifeKeeper IP resource (ip-sps-ers) to protect the ERS virtual IP address on node-a and node-b. Notice that the IP resource is being created on node-b and extended to node-a. Also note that the resulting resource should not be extended to node-c, the witness node. The icon indicates that the default option is chosen.

Field	Value
Create Resource Wizard
Switchback Type	intelligent
Server	node-b
IP Resource	10.20.0.20
Netmask	255.255.252.0
Network Interface	eth0
IP Resource Tag	ip-sps-ers
Pre-Extend Wizard
Target Server	node-a
Switchback Type	intelligent
Template Priority	1
Target Priority	10
Extend comm/ip Resource Hierarchy Wizard
IP Resource	10.20.0.20
Netmask	255.255.252.0
Network Interface	eth0
IP Resource Tag	ip-sps-ers

Once the IP resources have been created successfully, the LifeKeeper GUI should resemble the following image.

5. Right-click the ip-sps-ascs resource on node-a and click “Create Dependency…” Specify ilb-sps-ascs as the Child Resource Tag and click Create Dependency.

6. Right-click the ip-sps-ers resource on node-b and click “Create Dependency…” Specify ilb-sps-ers as the Child Resource Tag and click Create Dependency.

Once the dependencies have been created successfully, the LifeKeeper GUI should resemble the following image.

7. Add the following entries to /etc/hosts on node-a and node-b to allow resolution of each virtual host name to the frontend IP address of the corresponding load balancer. The entry for sps-ascs must also be added on node-d and node-e (the PAS and AAS hosts), as this virtual host name will be used to access the /export/sapmnt/SPS and /export/usr/sap/trans shared file systems.

10.20.0.10 sps-ascs
10.20.0.20 sps-ers

8. Test switchover and failover of the LB Health Check resource hierarchies as described in the Test LB Health Check Resource Switchover and Failover section of Responding to Load Balancer Health Checks. Correct any issues found or tune the parameters of the load balancer health checks as required to achieve successful operation.