HP Smart Array 5300 Controller User Guide

Drive Arrays and Fault Tolerance

B11

B10

B12

Figure D-3: Data striping (S1-S4) of data blocks B1-B12

For data in the logical drive to be readable, the data block sequence must be the same

in every stripe. This sequencing process is performed by the array controller, which

sends the data blocks to the drive write heads in the correct order.

A natural consequence of the striping process is that each physical drive in a given

logical drive will contain the same amount of data. If one physical drive has a larger

capacity than other physical drives in the same logical drive, the extra capacity is

wasted because it cannot be used by the logical drive.

The group of physical drives containing the logical drive is called a drive array (or

just array). Because all the physical drives in an array are commonly configured into

just one logical drive, the term array is also often used as a synonym for logical drive.

However, an array can contain several logical drives, each of a different size (refer to

Figure D-4).

HP Smart Array 5300 Controller User Guide D-3

HP CONFIDENTIAL

Writer: Kimberly Koch File Name: m-appd drive arrays and fault tolerance.doc

Codename: SilverHammer Part Number: 135606-006 Last Saved On: 3/13/03 2:02 PM