One of the new features in 12c is Global Data Services (GDS). GDS is basically the Oracle database service model but for replicated databases. Together they form a GDS configuration. In this post we’ll explore some of the high level components and design of GDS.
Before we describe the GDS components lets make it clear that this feature is intended for replication aware applications.
The following diagram shows an example GDS configuration.
Lets describe some of these components in a little more detail.
Global Data Services Pool
A GDS pool is a set of databases in a GDS configuration which provide a set of services. A database can only belong to one pool but can provide different services.
Global Data Services Region
A GDS Region is a set of databases in a GDS configuration which share network proximity. Each GDS Region can contain multiple GDS pools and these pools can also span regions
Global Service Manager
This software component is the management hub of GDS and it provides:
- service level load balancing
- centralized management
It is comparable to a remote listener but servicing multiple databases. It can only be associated with one GDS configuration and each region must have at least one global services manager but the recommendation is to have more than one to improve availability and performance.
Global Data Services Catalog
Similar to the RMAN catalog the the concept here is to have a repository to store configuration data in relation to GDS.
Oracle Notification Service Servers
ONS is used by GDS clients to receive high availability events.
Now that we know a little bit of the basics we’ll move on to installing GDS in Part 2.