Database Reference
In-Depth Information
Memory
To enable you to estimate the amount of memory needed in a BW on HANA implement-
ation, SAP Note 1637145 provides a program called get_size.zip. This program should be
extracted and executed against the existing BW implementation. The program will provide
the current row and column store sizes for your existing system. These sizes are then used
in the equation in Figure 2.6.
Figure 2.6: Rule-of-thumb for memory estimation
In this equation, 50 GB is allocated for HANA services and caches. The row store footprint
is divided by 1.5 as the expected compression for row store tables. The column store foot-
print is multiplied by 2 to allow space for runtime objects and temporary result sets in
HANA. The column store footprint is divided by 4 as the expected compression for column
store tables. The existing database compression variable represents any compression ap-
plied to the current BW system. If no compression exists, just enter a value of 1 for the
existing database compression variable.
Disk space
Disk space can be estimated with the equation in Figure 2.7.
Figure 2.7: Rule-of-thumb for disk space estimation
To estimate the disk space needed for the persistence layer, multiply the result of the
memory calculation in Figure 2.6 by 4. The log files will also require approximately as
much space as the overall system memory, so add this value to the result calculated in the
persistence layer to estimate the total overall disk space needed for the BW on HANA sys-
tem.
