RAID User Guide

2 RAID technology overview
This chapter defines the terms used in this guide and describes the RAID technologies supported by
select HP Business computers.
RAID terminology
Some of the terms in the following table have a broader meaning, but they are defined in relation to
the RAID implementation described in this guide.
Term Definition
Fault tolerance The ability of the computer to continue to operate if one drive fails. Fault tolerance is
often used interchangeably with reliability, but the two terms are different.
HDD One physical hard disk drive in the RAID array.
Option ROM A software module inside the system's BIOS that provides extended support for a
particular piece of hardware. The RAID option ROM provides boot support for RAID
volumes as well as a user interface for managing and configuring the system's RAID
volumes.
Primary drive The main internal HDD in the computer.
RAID array The physical drives that appear as one logical drive to the operating system.
RAID migration The change of data from a non-RAID to RAID configuration. “RAID level migration,” or
the change of data from one RAID level to another, is not supported.
RAID volume A fixed amount of space across a RAID array that appears as a single HDD to the
operating system.
Recovery drive The hard drive that is the designated mirror (copy of the primary) drive in a RAID 1 and
Recovery volume.
Reliability The likelihood—over a period of time—that a HDD can be expected to operate without
failure, also known as mean time before failure (MTBF).
Stripe The set of data on a single hard drive in a RAID volume.
Striping The distribution of data over multiple disk drives to improve read/write performance.
2 Chapter 2 RAID technology overview