on 2009 Jan 20 4:47 PM
Hello
We are thinking of adding the Java stack to our current 640 ABAP ERP2004 system.
We won't add any Java functionality as yet, we just want to be prepared if the requirement for Java stack comes up.
How can I 'calculate' the required additonal HW (CPU/Mem) for the addition of the Java stack.
I suppose there is some overhead (even when the Java functionality is not yet used)
Or would I get this info by ordering an EarlyWatch Check and specify our intention to add the Java stack ?
Any good/bad experiences in the field with a Java stack on 640 ?
Jo
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Hi Jo,
We've been running a dual stack for BW for a couple of years now. It is more cumbersome to apply fixes to both sides which therefore extends your downtime window and on occasion the JSPM process needs a kick start to complete the apply.
Keeping the java server in a separate memory pool will help performance - we created one with 4gig and followed the tuning note (71736) to get the buffers right and 990892 for the properties - but things may have moved on a bit here - there's a redpaper Java on IBM i5/OS worth a read.
We also required to use adobe printing and dbconnectivity to external SQL data bases which meant we had to install an application server; this also meant that we had to stay with the toolbox JDBC driver rather than the native JDBC driver which is faster. This I think also means we will be limited to staying on this driver rather than moving to the much better performing IT4J JVM when we upgrade to V6R1 shortly - is this the case Christoph ?
Regards
David
Hi David,
no, JVM and JDBC are two different things. When you upgrade your i5/OS to 6.1 you should definitely go to IT4J and this is not limited by any JDBC driver. As for the JDBC driver, it is true that you are limited to the toolbox driver when you are using remote application servers. You can't use the native driver then.
As for settings: The entry point for the Classic JVM is SAP note 717376 and for IT4J it is SAP note 1234382. When you want to cleanup settings (e.g. as advised in note 990892) my recommendation is to use the new CONFIGJVM tool which is described in SAP note 1262494. This greenscreen tool checks (and fixes) the most important parameters on all known places. You avoid the hassle of having to find all places manually via configtool and in several configuration files. CONFIGJVM is also the tool to use when you want to switch from Classic JVM to IT4J.
Best regards,
Christoph
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