Functional Description
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Logical Drive
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RAID Functions:
An Introduction
Redundant Arrays of Independent Disks, or RAID, offers the following
advantages: Availability, Capacity, and Performance. Choosing the
right RAID level and drive failure management can increase
Capacity and Performance, subsequently increasing Availability.
Infortrend's external RAID controllers provide complete RAID
functionality and enhanced drive failure management.
1.1 Logical Drive
Figure 1 - 1 Logical Drive
The advantages mentioned above are achieved by creating
“logical drives.” A logical drive is an array of independent
physical drives. The logical drive appears to the host as a
contiguous volume, the same as a local hard disk drive does.
The following section describes the different methods to create
logical arrays of disk drives, such as spanning, mirroring and
data parity. These methods are referred to as “RAID levels.”
1.2 Logical Volume
What is a logical volume?
The concept of a logical volume is very similar to that of a logical
drive. A logical volume is the combination of one or several logical
drives. These logical drives are combined into a larger capacity
using the RAID 0 method (striping). When data is written to a
logical volume, it is first broken into data segments and then striped
across different logical drives in a logical volume. Each logical drive
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