Change the Global Memory Allocation Limit

Change the Global Memory Allocation Limit

The SAP HANA database preallocates a pool of memory from the operating system over time, up to a predefined global allocation limit. You can change the default global allocation limit.

Prerequisites

You have the system privilege INIFILE ADMIN.

Context

The global_allocation_limit parameter is used to limit the amount of memory that can be used by the database. The unit for this parameter is MB. The default value is 0 in which case the global allocation limit is calculated as follows: 90% of the first 64 GB of available physical memory on the host plus 97% of each further GB. Or, in the case of small physical memory, physical memory minus 1 GB.

Changing this parameter does not require a restart.

Procedure

In the global.ini configuration file change the value of the global_allocation_limit in the memorymanager section.

You can enter a value for the entire system and for individual hosts. If you enter only a value for the system, it is used for all hosts. For example, if you have 5 hosts and you set the limit to 5 GB, the database can use up to 5 GB on each host (25 GB in total). If you enter a value for a specific host, then for that host, the specific value is used and the system value is only used for all other hosts. This is relevant only for multiple-host (distributed) systems.

Refer to the Workload Management section for details of other options for managing memory including setting a statement limit and admission control.