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1 Introduction

SAP HANA

SAP HANAä is a leading in-memory database and data management platform, specifically developed to take

full advantage of the capabilities provided by modern hardware to increase application performance. By

keeping all relevant data in main memory (RAM), data processing operations are significantly accelerated.

The key performance indicators of SAP HANA appeal to many of our customers, and thousands of deployments

are in progress. SAP HANA has become the fastest growing product in SAP’s history.

About this Document

A fundamental SAP HANA resource is memory. Understanding how the SAP HANA system requests, uses and

manages this resource is crucial to the understanding of SAP HANA. SAP HANA provides a variety of memory

usage indicators, to allow monitoring, tracking and alerting. This paper explores the key concepts of SAP

HANA memory utilization, and shows how to understand the various memory indicators.

2 What is Memory used for?

SAP HANA consists of a number of processes running on the SUSE Linux operation environment. Under Linux,

the operating system is responsible for the reservation of memory to all processes. When SAP HANA starts

up, the OS reserves memory for the program code (sometimes called the text), the program stack, and static

data. It then dynamically reserves additional data memory1

 when requested by the SAP HANA memory

manager. Dynamically allocated memory consists of heap memory and shared memory.

As an in-memory database, it is particularly critical for SAP HANA to carefully manage and track its

consumption of memory. For this purpose, SAP HANA manages its own data memory pool by requesting

memory from the OS, possibly in advance of using it. The memory pool is used to store all the in-memory

data and system tables, thread stacks, temporary computations and all the other data structures required for

managing a database.

At any given point, only parts of the memory pool are really in use. SAP refers to the total amount of memory

actually in use as the SAP HANA Used Memory. This is the most precise indicator of the amount of memory

that SAP HANA uses.

The SAP HANA Used Memory, consisting of code, stack and data, is shown below: