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Introduction

SAP Note 1495160 – SAP JVM as replacement for Partner JDKs 1.4.2 announcing the replacement for Partner JDKs 1.4.2 by SAP JVM 4. Just recently SAP officially released SAPJVM 4 for Windows, Solaris and Linux (not all types). The other platforms such as HP/UX, IBM i, AIX and more Linux types will follow in mid 2011.

The end of support for Partner JDK is set to October 1st 2012 for now. Date/time is still subject to change. This will affect all SAP Netweaver 6.40 and SAP Netweaver 7.0x AS Java based SAP systems.

Technical integration

SAPJVM 4 is not integrated in the same way as SAPJVM 5 or SAPJVM 6 or higher. From a technical point of view SAPJVM 5 is a separate Java component and can be updated automatically through JSPM. SAPJVM 5 and higher uses an ICM as dispatcher which is also a major technical difference.

A switch to SAPJVM 4 can take place automatically through the Switch Tool provided by SAP but operations like an update are to be done manually as SAPJVM 4 is not integrated as a separate Java component you cannot use JSPM to automatically update it. Since SAPJVM 4 doesn’t really touch the architecture, you will also have a dispatcher node as you would have when you run on Partner JDK.

This also means that when you look up SAP notes with a generic header like SAP Note 1133020 – How to import a SAP JVM patch into an AS Java you have to check the Affected Releases mentioned in the SAP note because this note and some other notes are not applicable to SAPJVM 4.

Switch tool

The preferred way to switch to SAPJVM 4 is using the switch tool provided by SAP. You can find information on the download location for the switch tool in SAP Note 1555341 – Downloading SAP JVM Switch Tool and SAPJVM 4. The switch tool uses SAPinst which is also used for SAP system installations so administrators should be familiar with how it works.

The switch tool runs you through a number of screens just like a traditional SAP installation would. Among those screens are screens which propose new parameter settings for the virtual machine as they can be very different depending on which partner JDK your virtual machine was running.

SAP Note 1522200 – SAP JVM 4.1 parameters when switching from a partner JDK provides an overview of the currently recommended parameters so I would recommend you check if the note is updated when you decide to switch to make sure the latest parameter recommendations are met.

Roll back changes in case of issues

If you bump into serious issues and you cannot get them resolved within an appropriate time frame there is the possibility to roll back the changes using instructions (script) which is written by SAPinst into the SAPinst installation directory. The file switchJDK.txt contains the instructions to roll back the changes.

Performance tests

The question should you do performance tests? I would say “yes”, of course it depends on how critical your applications are which are running on SAP Netweaver 6.40 / 7.0x AS Java based systems. If you have a SAP Netweaver Portal 7.0x for example which is used for ESS/MSS purposes I would recommend you go for performance tests / stress tests and compare the results from before and after the switch.

It stays a fact that the performance is not always better by default. Even if the performance is good you might want to try out a few different fine tuning parameters to further enhance performance based on the usage type of the system and the activities performed on it.

SAPJVM is based on the binaries provided by the Oracle (Sun) so you can check out whitepapers and documentation from Oracle to help you further tune your virtual machine. A rather compact whitepaper that is worth taking a look at is the Java Tuning White Paper.

Wily Introscope

The preferred monitoring tool for AS Java based SAP systems is still Wily Introscope. Most customers have Wily Introscope in place as part of the E2E Root Cause Analysis scenario on SAP Solution Manager (also referred to as diagnostics). In order to have proper interpretation of concurrent mark sweep garbage collection make sure your LM-Service support package stack level is up to date. It doesn’t necessarily mean you have to perform a support package stack upgrade (unless you are way behind on SPS level) but you at least should implement the latest bug fix patch available. 

One thing that might be confusing is the fact that the introscope agent probe directive sap_sapjvm.sar should not be enabled for SAPJVM 4 as it was build for SAPJVM 5.1 – SAP Netweaver 7.1 and is not compatible for SAPJVM 4.

Don’t forget that since you have a dispatcher it is recommended to integrate it into Wily Introscope as well. The procedure is described in the attachment of SAP Note 1424719 – Wily Introscope Instrumentation for SAP J2EE Dispatcher.

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11 Comments

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    1. Tom Cenens Post author
      Hello Daniel

      Thanks for your comment. I tried to keep it short and informative because I have received feedback on past blogs that they were too lengthy which makes it harder to digest.

      Kind regards

      Tom

      (0) 
    1. Tom Cenens Post author
      Hello Daniel

      Thanks for your comment.

      Yes they are supported, they always have been but they are not officially released yet at this moment in time.

      Official release and availability of download files for those OS’es will be mid 2011 according to the SAP note.

      I have participated in the customer pilot program and I tested SAP JVM 4 for HP/UX and AIX.

      Kind regards

      Tom

      (0) 
    1. Tom Cenens Post author
      Hello Juan

      Thanks for your comment.

      There are good reasons though to replace platform JDK with SAP JVM. For example better logging because SAP builds SAP JVM it means the error logs contain more information and the garbage collection logging also offers more detail.

      The SAP Notes also mention the pro’s why you should switch.

      I might do some small blogs on Wily Introscope and other tools on how to troubleshoot Java.

      Kind regards

      Tom

      (0) 
  1. Jonathan Wilson
    Hi Tom,

    Thanks for another well presented blog with excellent content. 

    My guess is that if you currently have a NetWeaver 7.0x technical system (e.g. Portal, BW, PI etc), rather than switching to the SAP JVM 4.1, you would most likely consider upgrading to NetWeaver 7.3 instead, and then you will be running on SAP JVM 6 anyway.

    Of course upgrading isn’t an option for NetWeaver Java systems that underpin Business Suite systems (e.g. CRM 7.0x Java), and in these cases you would need to consider switching JVMs as you have described.

    Obviously both options require significant effort, particularly in regards to regression testing.

    Cheers,
    Jon

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    1. Tom Cenens Post author
      Hello Jon,

      Thanks for your nice words.

      We support around two-hundred SAP systems. Some customers will upgrade to SAP Netweaver 7.3 in the near future but others will surely keep on running SAP Netweaver 7.0x till end of support of beyond.

      The tuning guide is of course also valid for SAP JVM 6 as the core engine of the different SAP JVM versions are exactly the same. The java classes and possibilities on top are different.

      Kind regards

      Tom

      (0) 
  2. Stefan Schiele
    Hi Tom,

    thanks for the quick but informative post about this topic!

    I have a question, maybe you had a similar situation.

    If i actually install a new netweaver 7.02 for example, i’d like to include the SAPJVM4 in the installion.
    Or – the better way – i’d ask my collegues who install the OS, to put the SAPJVM4 in their installation template for OS.

    How do you do, if you have to install a NW 7.02 at the moment?

    Thank you.
    Regards,
    Stefan

    (0) 

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