SAP on IBM i High Availability – Cluster Awareness
In our BLOG posting in October last year, Highly Available SAP on IBM i – Technical Reference, we described SAP on IBM i High Availability configurations using Power HA on hand of a technical reference. The reference explained how Power HA manages and monitors the database, file system, and SAP applications to provide switch-over and fail-over capability in the events of maintenance or failure.
The article today describes an extension to the HA architecture; namely, new integration of Power HA awareness into SAP management infrastructure. The enhancement is delivered by way of the latest SAP Kernel and SAP Host Agent patches according to SAP Note 1899637: “IBM i: PowerHA saphalib Integration”.
SAP instances under management of PowerHA are clustered resources (CRG). A clustered SAP instance is one that can migrate between the member nodes of a high availability cluster. At the heart of the new integration resides a connector with which SAP-Start-Service (SAPSTRSRV) communicates with PowerHA to recognize and control the state of clustered SAP instances.
The integrated PowerHA awareness provides the following new features:
- GUI Support for Clustered SAP instances via SAP MMC or SAP MC
- SAP Command Line control of Clustered SAP instances (sapcontrol)
- Consistent SAP instance Start and Stop
The picture below shows the architecture of the new support. The left of the picture shows typical management commands being issued by way of command or GUI. The issued commands are processed by a SAP-Start-Service agent as seen in the center of the picture. The SAP-Start-Service agent either communicates directly with its associated SAP instance (top right of the picture) or with PowerHA (middle right of the picture).
SAP Management of Clustered Instances
Both the SAP Microsoft MMC GUI and the Java based SAP MC provide menu items for observing and managing clustered SAP instances; the sapcontrol command line program offers the same features.
The screenshot of the SAP MMC in bottom left of the picture above shows the extended menu items enabled when SAP-Start-Service recognizes a clustered SAP instance. The table below explains how to use each of the methods.
|SAP Microsoft Management Console||
To enable the SAP MMC to monitor an IBM i instance, right click on the SAP Root branch of the MMC, select properties, then manually add the specification of at least one SAP instance for the <SID> (e.g. Central Instance: <sid> <host> <inst>: I70 as0090 09 [Add] + [OK]).
|JAVA based SAP Management Console||The java version is available by browser at http://<ibm_i_host>:5<inst>13/|
|Command Line sapcontrol Interface||
The command line interface for sapcontrol is available by 5250 terminal as <sid>adm and issuing:
==> sapcontrol PARAM(‘-nr <inst> -function <command>’)
or via QP2TERM or ssh shell as <sid>adm and issuing:
> sapcontrol -nr <inst> – function <command>
The primary sapcontrol commands that are affected by the integration are:
Consistent SAP Instance Start and Stop
Some typical automated SAP logistic operations use the ability to fully start and stop all SAP instances including the SAP Central Services instances (ASCS/SCS). With the integration patch, SAP-Start-Service is aware of those instances under influence of the PowerHA cluster manager. In such a case, SAP-Start-Service issues a state-full start-up and shutdown sequence; interacting with PowerHA to bring the SAP instance up or down. Short of this support, an instance shutdown might result in an SAP instance failover to anther node.
Highly Available configurations are complex in nature; the benefit is flexibility for maintenance and protection against system failure. Because the IBM i operating system integrates High Availability support for database, file system, and SAP applications, implementing a SAP HA solution on IBM i is basically as simple as it can be. The extended integration of PowerHA into SAP Landscape management described in this article brings SAP HA on IBM i even closer to seamless.