Introduction

RAID Volume

A RAID volume is created by joining two or more single-level arrays of the same RAID type. Unlike dual-level arrays, the arrays in a RAID volume do not have to be of equal capacity. In direct contrast to dual-level arrays, the second-level arrays in a RAID volume are not striped together, instead they are connected end-to- end.

Features

Optimized Disk Utilization

For simplicity the explanations of the various types of array above describe the arrays in terms of complete drives. Typically arrays use the same size drives, or if drives of varying capacities are used, the capacity used on each drive is limited to that of lowest capacity drive.

For example, a RAID-1 constructed using one 18G and one 9G drive will only use half of the capacity of the larger drive and the array will be limited to 9G.

Adaptec’s Optimized Disk Utilization feature allows arrays to be created using portion of drives. These sections of drives are known as segments and are created automatically during the array creation process.

Within a given array each segment will be the same size, but the segment size does not have to equal the capacity of the smallest drive.

Any unused capacity on drives is known as available space, and can be used in another array or arrays.

Adaptec RAID controllers use a small segment at the beginning of each drive connected to them to store information about the drives and arrays attached to the controller. This area is known as the RAID signature.

Array Reconfiguration

Adaptec RAID controllers support modifying existing arrays by expansion, migration from one array type to another and changing the stripe size.

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