Sizing for BW on HANA

Before migration of BW system to HANA database, we should determine the size of the SAP HANA required and the size of the BW system.

Sizing of SAP HANA system involves determining technical key points, CPU, main memory equipment, hard disk capacity, network bandwidth etc. Sizing of BW system requires determining compression factor, existing database size, data size of cold data not required in main memory (data in PSAs and write optimized dsos), table size etc.

Note: You can run the sizing report before and after cleaning up your BW system to determine the effectiveness of the cleaning process.

Fortunately, you don’t have to perform sizing of BW system yourself. You can use the sizing report provided by SAP for this task. The sizing report is already integrated with newer SAP BW systems. For older systems, the program can be executed manually. Refer SAP note 1736976 for more details on this.

If this is a new BW installation and you need to do initial sizing, you can run the SAP Quicksizer instead of sizing report (https://service.sap.com/quicksizer).

Sizing Report

In tcode SE38, enter the name of the report as /SDF/HANA_BW_SIZING and execute (F8).

[The screen shots below are from BW version 740 with patch level 09].

In the next screen, you can enter your parameters – give a unique file name and number of parallel processes used to run the report. Do not select too high number in production systems as all the system resources will be used for this report and the system performance will come down.

There is also an option to unload inactive tables which will not be considered for sizing and can be cleaned up later. Also, there are 3 levels of precision – High, Medium and Low. The higher the precision, the longer the report will take to run. There is not much difference in the results and you can always go for ‘Low’ precision report.

The report also provides option to select InfoProviders as shown in the screenshot below-

There is also a provision to specify future growth which is expected in near future for determining the memory sizes. You can specify the number of years and either a percentage or fixed data growth value-

You can also give any write optimized dsos which need to be considered for sizing. By default, write optimized dso represent cold data and will not be included in determining sizing.

Sizing report Part I

The above report provided following inferences-

• BW system currently includes 4.4 GB of data which will be available as row store tables later on
• BW system data that will be stored in column based tables will be 37 GB
• Breakdown of data size is shown in the report (infocube, dsos, psa, change logs etc.). Thus if you perform cleanup of change logs, you can save 2.5 GB of space as per the report.

Sizing report Part II

The sizing details report tells-

• current memory usage and memory after compression (74 / 92).
• 50 GB of memory is reserved exclusively for caches/services
• In total, 74 GB of memory is required for the analyzed BW system which is indicated under data [GB] column.
• In addition, some memory is required for temporary calculations, which is indicated under TOTAL [GB] INCL. TMP. column
• The minimum main memory requirement for the SAP BW on HANA system is therefore 92 GB

Sizing report Part III

This part of the report can be interpreted as-

• There is a need for only 1 server node of size 512 GB
• There will be 1 master node and no slave nodes (In big BW systems, you will have both multiple master nodes and slave nodes. Thus additional servers may be required for scale-out approach or more main memory size (1 TB) is required for scale-up approach)

You can see the text file saved in the home directory in AL11. You can save it in your local system from there.