Dell Studio 1749 (Early 2010) - Manual (Page 84)

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Drives and Media
RAID level 0 uses data striping to provide a high data access rate. Data
striping writes consecutive segments, or stripes, of data sequentially across
the physical drive(s) to create a large virtual drive. This allows one of the
drives to read data while the other drive is searching for and reading the next
block.
RAID 0 uses the full storage capacities of both drives. For example, two 120-
GB hard drives combine to provide 240 GB of hard drive space on which to
store data.
NOTE:
In a RAID 0 configuration, the size of the configuration is equal to the size of
the smallest drive multiplied by the number of drives in the configuration.
RAID Level 1
RAID level 1 uses data mirroring to enhance data integrity. When data is
written to the primary drive, the data is also duplicated, or mirrored, on the
second drive in the configuration. RAID 1 sacrifices high data-access rates for
data redundancy.