7.1 Understanding Arrays and Logical Drives

A logical drive is a group of physical disk drives that appears to your operating system as a single drive that can be used to store data.

The group of physical drives containing the logical drive is called a drive array, or just array. An array can contain several logical drives, each of a different size.

You can include the same disk drive in two different logical drives by using just a portion of the space on the disk drive in each, as shown in the following figure.

Disk drive space that has been assigned to a logical drive is called a segment. A segment can include all or just a portion of a disk drive's space. A disk drive with one segment is part of one logical drive, a disk drive with two segments is part of two logical drives, and so on. When a logical drive is deleted, the segments that comprised it revert to available space (or free segments).

A logical drive can include redundancy, depending on its RAID level. (See Selecting the Best RAID Level for more information.)

Protect your logical drives by assigning one or more hot spares to them. (See 6 Protecting Your Data for more information.)