HP 6-Port SATA RAID manual Raid

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RAID 1

A RAID 1 array is created by copying, or mirroring, all data from one drive onto a second drive. This mirroring provides redundancy, ensuring that if one drive fails no data is lost. However, redundancy also means that only half the total capacity is available.

Figure 4 A RAID 1 array

A RAID 1 array has no write performance advantage over a simple volume configuration, but it has improved read performance because the drives share read load equally.

RAID 5

This RAID type requires at least three drives. As in a RAID 0 array, data is striped across the drives. In addition, parity is generated to protect the data in a RAID 5 array and stored separately from data. The controller generates parity every time data is written to the array, and the parity is distributed in stripes across all drives. Parity uses a capacity equivalent to one drive. If a drive fails, the contents of the failed drive can be rebuilt from the data and the parity on the remaining drives.

Using parity minimizes the amount of storage space used to provide redundancy. Because only one drive is used to store parity, a three-drive array, which is the worst case, uses only one-third of the total capacity for redundancy. In larger arrays, the fraction of storage space used to provide redundancy decreases proportionately.

In the following figure, Pn represents the block of parity for the nth stripe of data.

Figure 5 A RAID 5 array

The write performance of a RAID 5 array is limited by the need to generate parity for every write. Read performance is good because the load is spread equally across all the drives.

Appendix D: About RAID 18

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Contents Port Sata RAID Controller Page Contents Board components and features Controller specifications and attributes1Controller specifications and attributes Installing the controller and drives Installation and configuration proceduresOverview of the installation process Installing the controller boardInstallation and configuration procedures Assigning the boot controller Creating a bootable arrayInstallation and configuration procedures Appendix a Electrostatic discharge Preventing electrostatic dischargeGrounding methods to prevent electrostatic discharge FCC rating label Appendix B Regulatory compliance noticesFederal Communications Commission notice Class a equipmentBsmi notice Canadian notice Avis CanadienEuropean Union regulatory notice ModificationsJapanese notice Korean notices Appendix C Using the RAID Configuration Utility Creating arraysViewing array properties Making an array bootableManaging arrays Deleting an array Initializing drives Managing failover drive assignmentsRescanning drives Spanned volume Types of volumes and arraysSimple volume Simple volume consists of a single driveRAID RAID 10 array RAID 50 array Glossary Array to fail and result in data loss Fault-tolerant arrayDegraded Example, 1040. See also channelLow-level format Records the RAID signature on the diskSystem as if it were a single storage unit Software for example, a missing driveSingle-level array VolumeOr concatenated, multiple regions of the same disk RAID 1 onIndex
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