Dell 720H2C RAID Level 1 Configuration, RAID Level 0+1 Configuration, RAID Level 5 Configuration

Another advantage of a RAID level 0 configuration is that it utilizes the full storage capacities of the 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 level 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 Configuration

RAID level 1 uses a data-redundancy storage technique known as "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. A RAID level 1 configuration sacrifices high data-access rates for its data redundancy advantages.

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.

NOTE: In a RAID level 1 configuration, the size of the configuration is equal to the size of the smallest drive in the configuration.

RAID Level 0+1 Configuration

A RAID 0+1 array combines the high data access rate of a RAID level 0 array and the data protection (redundancy) of a RAID level 1 mirror by striping data across two drives and mirroring that striped data on a second set of two drives.

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 240-GB on which to store data.

RAID Level 5 Configuration

RAID level 5 also 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. RAID level 5 is one of the most popular implementations of RAID.

RAID level 5 is faster than RAID level 1, but requires more hard drives than a RAID level 0 or RAID level 1 configuration.