Compaq Infortrend RAID Planning, Considerations, How many physical drives do you have?, Chapter

Chapter

2

RAID Planning

This chapter summarizes the procedures and provides some useful tools for first-time configuration:

2.1	Considerations:	things you should know before setting
		up
2.2	Configuring the	the most common configuration
	Array:	procedure
2.3	Operation Theory:	the theory behind data bus and system
		drive mapping
2.4	Functional Table of	a useful tool that helps you to quickly
	Contents	locate a firmware function

2.1Considerations

After you understand the basic ideas behind RAID levels, you may still be wondering about how to begin. Here are the answers to some questions that may help you through the decision making.

1. How many physical drives do you have?

When initially creating the drive groups, you should know how many drives you have in your RAID system or in the JBOD attached to the RAID controlling unit.

2. How many drives on each drive channel?

The optimal system planning is always a compromise between pros and cons. As a general rule, the number of drives you should connect on each channel equals the data bus bandwidth divided by the maximum transfer rate you can get from each of your hard drives. Knowing the mechanical performance of your hard drives can help to determine how many drives should be connected over a drive channel.

Always use fast and large drives of the same capacity for your disk array. A logical drive composed of an adequate number of

RAID Planning 2-1