IBM DS8000 manual Scalability for performance, Adding DDMs, Future plan

Table 6-2 Comparison of models for capacity

	2-way (Base	2-way +	4-way or LPAR	4-way or LPAR	4-way or LPAR
	frame only)	Expansion	(Base frame	+ Expansion	+ 2 Expansion
		frame	only)	frame	frames
Device adapters	2 to 8	2 to 8	2 to 8	2 to 16	2 to 16
	(1 - 4 Fibre Loops)
Drives	16 to 128	16 to 384	16 to 128	16 to 384	16 to 640
73 GB (15k RPM)	(increments of 16)	(increments	(increments	(increments	(increments
146 GB (10k RPM)		of 16)	of 16)	of 16)	of 16)
300 GB (10k RPM)
Physical capacity	1.1 to 37.2 TB	1.1 to 111.6 TB	1.1 to 37.2 TB	1.1 to 111.6 TB	1.1 to 186.3 TB

Adding DDMs

A significant benefit of the DS8000 series is the ability to add DDMs without disruption for maintenance. Even if it is difficult to take time for system maintenance for your system (for example, if you are operating a 24x7 online system), you don’t need to order larger capacity in advance to prepare for future growth. You can begin with a small configuration at first, and grow the capacity on demand without disruption.

Note: According to the announcement letter, the following activities are disruptive in the current status:

￿Field attachment of a Model 92E with the 922

￿Field attachment of a Model 9AE with the 9A2

In both cases, only when the first expansion frame is attached to the base frame, you do need a disruptive maintenance. The first expansion enclosure for the Model 922 and 9A2 has I/O enclosures and these I/O enclosures must be connected into the current RIO-G loops. Currently, this operation is not supported non-disruptively.

If you install the base frame and the first expansion frame for the Model 922 or 9A2 at the beginning, you don’t need a disruptive upgrade to add DDMs. The expansion enclosure for the DS8100 and the second expansion enclosure for the DS8300 has no I/O enclosure, therefore you can attach them to the existing frame without disruption.

Future plan

In addition, the architecture is designed to scale with 300 GB disk technology up to 1 PB. 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.

6.3.2 Scalability for performance

The DS8000 series also has linear scalability for performance. This capability is due to the architecture of the DS8000 series.

110DS8000 Series: Concepts and Architecture