Memory performance requirements
RAM performance metrics such as seek time or memory bandwidth, are strictly dependent on the memory type, which is linked with the processor type.
Restriction: Do not run your server on a virtual machine for which memory compression
was enabled, for example in x86 virtualization that is provided by VMware. It is especially
important in case of the computer on which the DB2® database is
running.
Pay particular attention to the amount of memory that is available
for License Metric Tool and the DB2 application. It is important to monitor the RAM usage on
a daily basis because memory usage differs greatly depending on how
the application is being used. The main factors besides the environment
size include:
- The number of concurrent web UI users
- The frequency of data imports
Memory monitoring is especially important on the database computer
as insufficient amount of RAM can significantly slow down background
tasks, such as PVU data aggregation because of memory swapping. Swapping,
also known as paging, is the use of secondary disk storage to store
and retrieve application data for use in RAM. It is automatically
performed by the operating system and typically occurs when the available
RAM is depleted. Swapping can have a significant impact on DB2 performance and should be avoided.
To avoid swapping, ensure that sufficient RAM is available on the
computer so processes do not consume all the available RAM. Use the
following Linux® tools to monitor
RAM usage and memory swapping:
- top
- free
- vmstat
- or sar
If you notice that there is almost no free memory available to License Metric Tool and the DB2 processes are being swapped to disk, the best solution is to increase the RAM memory size.