IBM manual Rio-G, Benefit of the DS8000 for scalability

4-way I/O controllers		Hosts
Host		Device
Adapter		Adapter
Processor Complex
Data Cache
and		I/O
Persistent
	Enclosure
Memory
2-way		RIO-G
processor
		Disks
Figure 6-7 4-way model components

These two figures describe the main components of the I/O controller for the DS8000 series. The main components include the I/O processors, data cache, internal I/O bus (RIO-G loop), host adapters, and device adapters. Figure 6-6 on page 111 is a 2-way model and Figure 6-7is a 4-way model. You can easily see that, if you upgrade from the 2-way model to the 4-way model, the number of main components doubles within a storage unit.

For further information about performance for the DS8000 series, see Chapter 12, “Performance considerations” on page 253.

Future Plan

According to the announcement letter, IBM has issued the following Statement of General Direction:

Future models in the series are planned to provide customers additional flexibility and scalability. IBM next plans to provide 8-way processors with corresponding scalability from the 2-way and 4-way models currently offered. In addition, physical capacity will be scalable through increased disk drives within a configuration.

In the 8-way model, the number of main components is four times that of a 2-way model.

The benefit of the DS8000 for scalability

Because the DS8000 series adopts this architecture for the scaling of models, the DS8000 series has the following benefits for scalability:

￿The DS8000 series is easily scalable for performance and capacity.

￿The DS8000 series architecture can be easily upgraded.

112DS8000 Series: Concepts and Architecture