IBM manual DS8000 Host Systems Attachment Guide, Planning, Capacity planning considerations

General considerations

In this section we cover some topics that are not specific to a single operating system. This includes available documentation, some planning considerations, and common tools.

The DS8000 Host Systems Attachment Guide

The DS8000 Host Systems Attachment Guide, SC26-7628 provides instructions to prepare a host system for DS8000 attachment. For all supported platforms and operating systems it covers:

￿Installation and configuration of the FC HBA

￿Peculiarities of the operating system with regard to storage attachment

￿How to prepare a system that boots from the DS8000 (when supported)

It varies in detail for the different platforms.

Many more publications are available from IBM and other vendors. Refer to Chapter 15, “Open systems support and software” on page 319 and to the operating system-specific sections in this chapter.

Planning

Thorough planning is necessary to ensure that your new DS8000 will perform efficiently in your data center. In this section we raise the questions you will have to ask and the things you have to consider before you start. We don’t cover all the items in detail because this is not an implementation book.

For a more detailed discussion of these considerations related to performance, refer to Chapter 12, “Performance considerations” on page 253.

Capacity planning considerations

For proper sizing of your DS8000 storage subsystem more than the total required capacity has to be known. Consider the following questions:

￿What is the capacity for each host system or even each application? What are this system’s performance requirements (I/Os, throughput)?

￿How much capacity is needed for fixed block (open systems) and how much for CKD (mainframe) data?

￿Do you need advanced copy functions?

￿Which DS8000 model is adequate to achieve capacity and performance requirements?

￿What is the number of disk drives needed, their size and speed?

￿With the usable capacity known, what is the raw capacity to order?

￿What is the number of Fibre Channel attachment needed?

￿Do you have to plan for future expansion? Is Capacity on Demand an option?

Data placement considerations

A DS8000 logical volume is composed of extents. These extents are striped across all disks in an array (or rank, which is equivalent). To create the logical volume, extents from one extent pool are concatenated. Within a given extent pool there is no control over the placement of

344DS8000 Series: Concepts and Architecture