To protect the SAP System, an SAP Hierarchy will be needed. This SAP Hierarchy consists of the Core (Central Services) Resource, the ERS Resource, the Primary Resource and Secondary Resources. To create this hierarchy, perform the following tasks from the Primary Server. Note: The below example is meant to be a guideline for creating your hierarchy. Tasks will vary somewhat depending upon your configuration.
Create the Core Resource
- From the LifeKeeper GUI menu, select Edit, then Server. From the drop-down menu, select Create Resource Hierarchy.
A dialog box will appear with a drop-down list box with all recognized recovery kits installed within the cluster. Select SAP from the drop-down listing.
Click Next.
When the Back button is active in any of the dialog boxes, you can go back to the previous dialog box. This is especially helpful should you encounter an error that might require you to correct previously entered information.
If you click Cancel at any time during the sequence of creating your hierarchy, LifeKeeper will cancel the entire creation process.
- Select the Switchback Type. This dictates how the SAP instance will be switched back to this server when it comes back into service after a failover to the backup server. You can choose either intelligent or automatic. Intelligent switchback requires administrative intervention to switch the instance back to the primary/original server. Automatic switchback means the switchback will occur as soon as the primary server comes back on line and re-establishes LifeKeeper communication paths.
The switchback type can be changed later, if desired, from the General tab of the Resource Properties dialog box.
Click Next.
- Select the Server where you want to place the SAP PAS, ASCS or SCS (typically this is referred to as the primary or template server). All the servers in your cluster are included in the drop-down list box.
Click Next
- Select the SAP SID. This is the system identifier of the SAP PAS, ASCS or SCS system being protected.
Click Next.
- Select the SAP Instance Name (ex. ASCS<No.>) (Core Instance first) for the SID being protected.
Note: Additional screens may appear related to customization of Protection and Recovery Levels.
- Select the IP Child Resource. This is typically either the Virtual Host IP address noted during SAP installation (SAPINST_USE_HOSTNAME) or the IP address needed for failover.
- Select or enter the SAP Tag. This is a tag name that LifeKeeper gives to the SAP hierarchy. You can select the default or enter your own tag name. The default tag is SAP-<SID>_<ID>.
When you click Create, the Create SAP Resource Wizard will create your SAP resource.
- At this point, an information box appears and LifeKeeper will validate that you have provided valid data to create your SAP resource hierarchy. If LifeKeeper detects a problem, an ERROR will appear in the information box. If the validation is successful, your resource will be created. There may also be errors or messages output from the SAP startup scripts that are displayed in the information box.
Click Next
- Another information box will appear explaining that you have successfully created an SAP resource hierarchy, and you must Extend that hierarchy to another server in your cluster in order to place it under LifeKeeper protection.
When you click Next, LifeKeeper will launch the Pre-Extend Wizard that is explained later in this section.
If you click Cancel now, a dialog box will appear warning you that you will need to come back and extend your SAP resource hierarchy to another server at some other time to put it under LifeKeeper protection.
- The Extend Wizard dialog will appear stating Hierarchy successfully extended. Click Finish.
- The Hierarchy Integrity Verification dialog appears. Once Hiearchy Verification finishes, click Done to exit the Create Resource Hierarchy menu selection.
Create the ERS Resource
The ERS resource provides additional protection against a single point of failure of a Core Instance (Central Services Instance) or enqueue server process. When a Core Instance (Central Services Instance) fails and is restarted, it will retrieve the current status of the lock table and transactions. The result is that, in the event of the enqueue server failure, no transactions or updates are lost and the service for the SAP system continues.
Perform the following steps to create this ERS Resource.
- For this same SAP SID, repeat the above steps to create the ERS Resource selecting your ERS instance when prompted.
- You will then be prompted to select Dependent Instances. Select the Core Resource that was created above, and then click Next.
- Follow prompts to extend resource hierarchy.
- Once Hierarchy Successfully Extended displays, select Finish.
- Select Done.
Note: The Enqueue Replication Server (ERS) resource will be in-service (ISP) on the primary node in your cluster. However, the architecture and function of the ERS requires that the actual processes for the instance run on the backup node. This allows the standby server to hold a complete copy of the lock table information for the primary server and primary enqueue server instance. When the primary server running the enqueue server fails, it will be restarted by SIOS Protection Suite on the backup server on which the ERS process is currently running. The lock table (replication table) stored on the ERS is transferred to the enqueue server process being recovered and the new lock table is created from it. Once this process is complete, the active replication server is then deactivated (it closes the connection to the enqueue server and deletes the replication table). SIOS Protection Suite will then restart the ERS processes on the new current backup node (formerly the primary) which has been inactive until now. Once the ERS process becomes active, it connects to the enqueue server and creates a replication table. For more information on the ERS process and SAP architecture features, visit http://help.sap.com and search for Enqueue Replication Service.
Create the Primary Application Server Resource
- Again, for this same SAP SID, repeat the above steps to create the Primary Application Server Resource selecting DVEBMGS{XX} (where {XX} is the instance number) when prompted.
- Select the Level of Protection when prompted (default is FULL). Click Next.
- Select the Level of Recovery when promted (default is FULL). Click Next.
- When prompted for Dependent Instances, select the “parent” instance, which would be the ERS instance created above.
- Select the IP Child Resource.
- Follow prompts to extend resource hierarchy.
- Once Hierarchy Successfully Extended displays, select Finish.
- Select Done.
Create the Secondary Application Server Resources
If necessary, create the Secondary Application Server Resources in the same manner as above.
Note: For command line instructions, see Setting Up SAP from the Command Line.
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