Dell Studio 1558 (Early 2010) - Manual (Page 87)

Drives and Media
87
RAID Level 5 Configuration
RAID level 5 uses data parity. RAID level 5 stripes both data and parity
information across three or more drives. It provides data striping at the byte
level and also stripe error correction information (rotating parity array). This
results in excellent performance and good fault tolerance.
If a drive failure occurs, subsequent read and write operations are directed to
the other surviving drives. A replacement drive can then be rebuilt using the
data from the surviving drives. Also, because data is duplicated on the primary
and additional drives, four 120-GB RAID level 1 drives collectively have a
maximum of 360-GB on which to store data.
Setting Your Computer to RAID-Enabled Mode
Before creating a RAID configuration, you must set your computer to RAID-
enabled mode.
1 Enter the system setup program (see "Entering the System Setup Program"
on page 308).
2 Press the up- and down-arrow keys to highlight Drives, and then press
<Enter>.
3 Press the up- and down-arrow keys to highlight the applicable hard drive,
and then press <Enter>.