Netgear EDA 500 User Manual

To get the most out of your ReadyNAS storage system, it is helpful to understand the basics of volumes
and RAID. Understanding these concepts is the first step to making good decisions about how to configure,
manage, and use your ReadyNAS storage system.

In the most general sense, volumes are data storage devices. Your computer treats an internal hard drive
as a volume. It also treats a portable USB thumb drive as a volume.

Volumes can be either physical or logical. Usually, the term physical volume refers to a hard disk drive.
When this term is used in this way, a two-bay storage system can have up to two physical volumes (hard
disk drives). A four-bay storage system can have up to four physical volumes. A six-bay storage system
can have up to six physical volumes.

The term logical volume refers to the way that you divide, or partition, your storage space. For example:

Each logical volume can correspond to a hard disk drive.

A logical volume can be made up of more than one hard disk drive.

In this manual, the term volume refers to a logical volume. The terms hard disk drive and disk refer to a
physical volume.

Your ReadyNAS storage system allows you to configure your hard disks using one of the many RAID
technologies.

RAID is short for redundant array of independent disks. RAID is a storage technology that balances data
protection, system performance, and storage space by determining how the storage system distributes
data. Many different ways of distributing data have been standardized into various RAID levels. Each
RAID level offers a tradeoff of data protection, system performance, and storage space. For example,
one RAID level might improve data protection but reduce storage space. Another RAID level might increase
storage space but also reduce system performance.

Your ReadyNAS storage system supports X-RAID™ mode, a proprietary single-volume RAID architecture
that is easy to administer, and Flex-RAID mode, which allows you to format your disks in a variety of
industry-standard RAID levels.

When you power on your system for the first time or if you reset your system to its factory default settings,
the optimal RAID mode and level are automatically selected for you based on the number of disks that
are installed. You can also configure the RAID settings manually (see 

 on page 24).

X-RAID is an auto-expandable RAID technology that is available only on ReadyNAS systems. With X-RAID,
you do not need to know intricate details about RAID to administer your system. X-RAID allows you to
add storage space without reformatting your drives or moving your data to another location. Because the