A distributed SAP HANA system is a system that is installed on more than one host. Otherwise it is a single-host system.An SAP HANA system is identified by a system ID (SID). It is perceived as one unit from the perspective of the administrator, who can install, update, start up, shut down, or back up the system as a whole
An SAP HANA system can be distributed across multiple hosts for reasons of scalability and availability.A multiple-host or distributed SAP HANA system is a system that is installed on more than one host. Otherwise, it is a single-host system.
An SAP HANA system installed on multiple hosts is identified by a single system ID (SID). It is perceived as one unit from the perspective of the administrator, who can install, update, start up, or shut down the system as a whole. The different databases of the system share the same metadata and requests from client applications can be transparently dispatched.
The main reason for distributing a system across multiple hosts is scale-out. A multiple-host system can overcome hardware limitations of a single physical server, and it can distribute the load between multiple servers. Distributing a system also supports failover. One or more hosts can be configured to work in standby mode, so that if an active hosts fails, a standby host automatically takes its place. The index servers on standby hosts do not contain any data and do not receive any requests.
For more information about hosts, including host roles, fail-over configuration, and storage options, see the SAP HANA Server Installation and Update Guide.
In a multiple-host system each index server is usually assigned to its own host for maximum performance. SAP HANA supports different ways of distributing data across the hosts:
- Different tables can be assigned to different index servers.
- A table can be split, or partitioned, in a way that different rows of the table are stored on different index servers