A RAID (Redundant Array of Independent Disks) is a data storage scheme that uses two or more drives
accessed in combination to improve fault tolerance. Initially used with servers, desktop PCs are increas-
ingly using RAID controller and extra ATA or SCSI disks. Newer system boards often have RAID controllers.
This section provides a brief explanation of RAID configurations.
Even though HP supports RAID 0, it is not the recommended configuration for business PC users. Lack of
redundancy causes less than half the reliability of a single hard drive system since the Mean Time
Between Failure (MTBF) of RAID 0 is equal to the MTBF of an individual drive, divided by the number of
drives.
Because it is a very cost-effective way to increase system storage reliability and a great value proposition,
RAID 1 is the only RAID configuration that HP preconfigures for HP Compaq dc5750 Business PCs. RAID
1 provides high availability with minimal performance impact, as well as greater reliability compared to
a single hard drive configuration.
RAID 1 has redundancy and hence is a true RAID. It more than doubles reliability because the MTBF of
RAID 1 is equal to the MTBF of an individual drive multiplied by the number of drives (2). In other words,
the probability of one hard drive failure on a given day is the square root of that same probability. Hypothetically, if the chances that a single hard drive fails is 1:2000, with RAID 1 the chance that both of your
hard drives fail is 1:4,000,000.
Mirroring, segmentation, and striping have no real meaning in RAID 1 . In the table and graphic, the data is arranged in rows for representation of different pieces of data.
This level is more or less the same as Level 0, with the one difference that it does provide a certain degree of fault tolerance.
This level provides users with data striping at the byte level, along with stripe error correction info. The result is superior performance and good fault tolerance.
