SAP HANA is a platform that serves to replace the classical hard disk-based data storage system with an in-memory alternative. The SAP HANA Acronym stands for (High-performance ANalytic Appliance). While HANA serves as a replacement for classical hard disk-based storage systems, it should be understood that it is more than just a replacement. While HANA can perform any and all features of a traditional DBMS, it also provides many benefits that a classical database server does not. Let’s begin our over an overview of SAP HANA by contrasting it to the traditional DBMS.
As a refresher, let’s recall how a classical database works. A DMBS manages an array of HDDs that store data in a row based format. Using INSERTS, READS, UPDATES and QUERIES, the database allows users to persist, retrieve, and manage data on demand. The principal drawback of a classical database is the fact that it uses HDDs. Reading, writing, and searching using HDD is an inherent bottleneck of any classical database. Hard disk drives are mechanical devices, requiring a rotating magnetized platter that stores binary data, and a read/write head that accesses and reads that data. (see below)
Although many advances have been made over the years to improve HDD technology speed and storage capability, the HDD can never match the speed of computer memory. Enter SAP HANA and its in-memory data storage. By storing the vast majority of data in memory, HANA sidesteps the costly action of reading data from HDDs to provide data to users. Since retrieving data from computer memory is 100,000 times faster than retrieving data from HDDs on average, the speed increases are exponential and instantaneous. Simply changing the architecture from HDD based to memory-based storage is enough to provide drastic speed increases on its own, but SAP HANA takes it a step further by providing features on top of this in-memory platform. This allows for even greater speed of access, data retrieval, and data processing.
As illustrated in the following diagram, the basic system architecture has a classic 3-tier approach:
There is a distinction between the overall SAP HANA system and the SAP HANA XS advanced application server. The SAP HANA system refers to the entire SAP HANA platform part of the integrated solution. The SAP HANA XS advanced application server describes only the runtime platform as an integral part of the solution. All services of the SAP HANA system share the same system identifiers (that is, instance number and SID) and are controlled by the hdbdaemon service.
The third tier, represented by an SAP HANA database, provides persistence services, that is, data storage. In contrast, the application server components in the middle tier are responsible for deploying, running, and monitoring the applications. Most security-related features such as authentication, authorization, and auditing are primarily enforced in this layer. End users interact on the client layer with the system or business users that are authenticated by an identity provider (IdP), which is SAP HANA user management by default. However, both the server components and the applications themselves access the SAP HANA database only through technical database users that the platform generates implicitly. Direct access to the database is only intended for database administration purposes.
The following diagram provides a more detailed overview of the technical system landscape of the XS advanced application server. All relevant components and storages used by the application server layer are highlighted with a gray background.