Scale out deployments offer superior scale and additional high availability options in comparison to Scale Up deployments. Multiple nodes or servers are combined into a single system. Scale out systems allow for each host to be given a specific role:
|
Host Role |
Description |
|---|---|
|
Worker |
A worker host is used for database processing. |
|
Standby |
A standby host is available for failover in a high availability environment. |
|
Extended Storage Worker |
Worker host for SAP HANA dynamic tiering. |
|
Extended Storage Standby |
Standby host for SAP HANA dynamic tiering. |
|
ets_worker |
Worker host for SAP HANA accelerator for SAP ASE. |
|
ets_standby |
Standby host for SAP HANA accelerator for SAP ASE. |
|
streaming |
Host for SAP HANA streaming analytics. |
|
xs_worker |
Host for SAP HANA XS advanced runtime. |
|
xs_standby |
Standby host for SAP HANA XS advanced. |
Within this guide, only worker and standby hosts are used. Additional hosts can be added with other roles.
Each worker host in the scale out landscape requires its own data and log volume. In the event of a worker failing and a standby being present, the failed worker volumes will be attached to the standby and the relevant services started to provide high availability.
The following volumes and size recommendations are created before installation:
|
Volume |
Size |
Purpose |
|---|---|---|
|
Installation |
Installation size = Minimum 1 x RAM of worker host x number of hosts. See the section on Shared Filesystem for Scale Out SAP HANA. |
Contains run-time binaries, installation scripts and other support scripts. This also contains the SAP HANA configuration files, trace files, and profiles. |
|
Data |
Data size = 1 x Amount of RAM |
SAP HANA persists a copy of the in-memory data to this location. This is achieved by writing changed data in the form of savepoints. |
|
Redo Log |
For systems <512GB, Redo Log size = 1/2 RAM For systems >512GB, Redo Log size = 512GB or lager |
Each transaction performed on the database is recorded to this location in the form of a redo log entry. |
Block based volumes on FlashArray are provided with a capacity limit at creation.
File services based directories must have a Quota Policy applied to restrict capacity use.
Below is an example of a 3 Terabyte capacity limit applied in the graphical user interface to all of the directories for a scale out instance :