Dell Precision T5400 User's Guide - Page 51

RAID Level 1 RAID level 1 uses a data-redundancy storage technique known as "mirroring." When data is written to the primary drive, the data is then duplicated-or mirrored-on the other drive. A RAID level 1 configuration sacrifices high-data access rates for its data redundancy advantages. serial ATA RAID configured for RAID level 1 segment 1 segment 2 segment 3 segment 4 segment 5 segment 6 hard drive 1 segment 1 duplicated segment 2 duplicated segment 3 duplicated segment 4 duplicated segment 5 duplicated segment 6 duplicated hard drive 2 If a drive failure occurs, subsequent read and write operations are directed to the surviving drive. A replacement drive can then be rebuilt using the data from the surviving drive. Also, because data is duplicated on both drives, two 120-GB RAID level 1 drives collectively have a maximum of 120-GB on which to store data. RAID Level 5 RAID level 5 uses a data-staging storage technique known as "parity checking." When a block of data is written to the RAID configuration, it is striped across all of the drives in the RAID array except for one drive, to which is written parity data. The parity data is information that allows for the entire block of striped data to be calculated if one of the drives fails. Advanced Features 51