Why use the calculator?
GPDB virtual memory calculator estimates the best virtual memory settings based on existing large scale deployments. The linux kernel is very good at optimizing its own memory, but we still have to ensure we do not overallocate GPDB memory resulting in out of memory events. This calculator helps the user reserve a conservative amount of memory for kernel while maximizing the amount of memory used by GPDB.
For more information refer to GPDB documentation
Recommended Max Settings
Value is in MB and configured in postgresql.conf which is controlled by the gpconfig command
Value is a percentage and configured in /etc/sysctl.conf
Choose the value for Primary Segments Per Node based on your mirroring strategy. See GDPB Documentation for more information on group and spread mirroring strategies
- Given a configuration of 6 primaries and 6 mirrors we should set Primary Segments Per Node to 6+6=12 when using group mirroring
- Using the same configuration example for spread mirroring the value would be 6+2=8