Introduction
For performance reasons SAP recommends not to use dual stack SAP systems anymore, especially for SAP Netweaver BW. Now there are still customers out there running SAP Netweaver BW who have a dual stack installation requesting a split of their current environment into two single stack SAP systems (BI ABAP + DATABASE and BI JAVA + DATABASE).
Splitting a SAP Netweaver BW 7.0x Dual Stack using SAPinst export/import is not supported but not impossible either.
Caution advised
It’s not the intention to go and get everyone on board to go do unsupported work. I have written in some of my blogs that I interpret “impossible or not supported” as “not been done yet” and this sometimes pops up while I’m at work and as a consequence I won’t hesitate to try something out. Writing it without given any example is not really clean so this blog can serve as an example.
If in the past no one started cutting open a corpse to learn more about the human body, they would not know as much as they know today but someone had to start doing it.
Procedure
- export the java stack out of the dual stack SAP system (source SAP system)
- install of the Java only SAP system using the export that was done (one of the target SAP systems)
- remove the java stack from the source SAP system (thus creating the second target SAP system by doing so)
- perform the switch operation (configuration settings) to couple both single stacks (BI Java <-> BI ABAP) together
- drink a coffee when it’s done
Exporting the java stack
picture 1.1
Exporting the java stack is done by using the regular procedure (you can follow the SAP guide available).
After starting SAPinst you choose product -> additional software life-cycle tasks -> system copy -> <database> -> source system -> central system -> based on AS ABAP and AS Java -> Database and Central Instance (see picture 1.1).
picture 1.2
On the screen with header SAP System > Database Export you only select the Java Schema (see picture 1.2).
Continue and let SAPinst export it and finish
Result is that after this procedure you have an export directory with your Java stack.
Importing the java stack into a Java only SAP system (BI Java)
picture 1.3
In SAPinst you choose product -> additional software life-cycle tasks -> system copy -> <database> -> target system -> central system -> Based on AS Java -> Central System Installation (see picture 1.3).
Once you are in the first screen, stop sapinst (don’t clean up). Pick to option so you can continue sapinst later.
SAPinst XML files
A short interruption and some information on SAPinst XML files.
In the directory from which you run SAPinst you also have the XML files which SAPinst uses:
- dialog.xml
- used to build up the screen (labels, text, input fields, radio buttons and so on)
- control.xml
- controls the SAPinst process (java coding to perform checks and make changes accordingly)
- messages.xml
- contains the possible (error) messages shown in SAPinst
- keydb.xml
- in this file all the information SAPinst provides is written (some automatic like checking which SAP systems already reside on the server, some after you have filled in input fields and clicked next)
It’s possible to modify one or more of these xml files and start SAPinst up again. When SAPinst starts up again it will read those xml files (to know where you left off and what parameter values are set etc) and continue the installation. This can serve for many different purposes:
- automating an installation is possible by having a completed keydb.xml, analyzing it and auto filling it by altering values for another installation, given it is the same product that needs to be installed.
- making an input field available that was grayed out like the database host field when you wanted to perform a MCOD (multiple components one database) installation. According to official documentation it’s only possible through high availability installation, I have done it in the past using the regular central system installation option by modifying the dialog.xml and control.xml and it worked (there were additional other manual actions to be performed after installation finished).
- inserting additional default parameters before your SAP system is installed. For example you want to already include the default transport directory parameter DIR_TRANS, it is possible by inserting the relevant line on the correct position in keydb.xml.
The modifications
The question is where does it go wrong? SAPinst will notice that the export you have and place available is from a dual stack SAP source system (due to the labels, files and folders that are part of the export). Because of this, the SAPinst installer will know and will throw an error that it’s not possible to import an export taking from a dual stack (although you only selected java stack) into a single stack Java.
"Importing the Java dump from a double stack system into a Java Only system is not supported."
This is checked by the control.xml file using some java coding:
if (!hasABAP && hasJava) {
ASSERT(arguments.callee, sourceInstanceIsJavaOnly, "Importing the Java dump from a double stack system into a Java Only system is not supported.");
}
Throwing out these lines from control.xml (perhaps I threw out or changed more lines but it’s not my intention that everyone will start doing unsupported work), saving control.xml and starting up SAPinst again and the import of a Java dump from a double stack system into a Java Only system can begin.
Alternative procedure (supported)
- Place everything you have of custom development on your source Java stack in transport requests (using CTS+ for example).
- Capture as many things from your source Java stack you cannot place in transport requests (certain settings etc for which there is no possibility to transport).
- Install a java only SAP system.
- Remove the java stack of your dual stack SAP system.
- Perform the configuration as you would normally do with a new installation of two single stack SAP systems that are to be connected for BW scenario.
- Import your custom development (CTS+ again for example).
- Put your settings (which couldn’t be transported) in place again.
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