Dell UCP-60, UCP-61, UCC-60 manual RAID Description, Summary of RAID Levels

RAID Description

RAID is a group of independent physical disks that provides high performance by increasing the number of drives used for saving and accessing data. A RAID disk subsystem improves I/O performance and data availability. The physical disk group appears to the host system either as a single storage unit or multiple logical units. Data throughput improves because several disks are accessed simultaneously. RAID systems also improve data storage availability and fault tolerance. Data loss caused by a physical disk failure can be recovered by rebuilding missing data from the remaining physical disks containing data or parity.

NOTICE: In the event of a physical disk failure, a RAID 0 virtual disk fails, resulting in data loss.

Summary of RAID Levels

RAID 0 uses disk striping to provide high data throughput, especially for large files in an environment that requires no data redundancy.

RAID 1 uses disk mirroring so that data written to one physical disk is simultaneously written to another physical disk. RAID 1 is good for small databases or other applications that require small capacity, but also require complete data redundancy.

RAID 5 uses disk striping and parity data across all physical disks (distributed parity) to provide high data throughput and data redundancy, especially for small random access.

RAID 6 is an extension of RAID 5 and uses an additional parity block. RAID 6 uses block-level striping with two parity blocks distributed across all member disks. RAID 6 provides protection against double disk failures and failures while a single disk is rebuilding. If you are using only one array, deploying RAID 6 is more effective than deploying a hot spare disk.

RAID 10, a combination of RAID 0 and RAID 1, uses disk striping across mirrored disks. It provides high data throughput and complete data redundancy. RAID 10 can support up to eight spans, and up to 32 physical disks per span.

RAID 50, a combination of RAID 0 and RAID 5, uses distributed data parity and disk striping and works best with data that requires high system availability, high request rates, high data transfers, and medium-to-large capacity.

RAID 60 is a combination of RAID 6 and RAID 0, a RAID 0 array is striped across RAID 6 elements. RAID 60 requires at least 8 disks.

Overview

17