By default, SAP HANA can pre-allocate up to 90% of the available physical memory on the host. There
is normally no reason to change the value of this variable, except in the case where a license was purchased for less than the total of the physical memory. In such a case, you should change the global allocation limit to remain in compliance with the license.
You have a server with 512GB, but purchased an SAP HANA license for only 384 GB.
You therefore set the global_allocation_limit to 393216 (384 * 1024 MB).
You have a distributed HANA system on four hosts with 512GB each, but purchased an SAP HANA license for only 768 GB. Set the global_allocation_limit to 196608 (192 * 1024 MB on each host).
Tags: How to configure HANA memory allocation, Memory Consumption Configuration,