Promise Technology EX8654, EX8658, EX8650, EX4650 RAID 5 Block Striping with Distributed Parity

Chapter 7: Technology Background

RAID 5 – Block Striping with Distributed Parity

RAID 5 organizes block data and parity data across the physical drives. Generally, RAID Level 5 tends to exhibit lower random write performance due to the heavy workload of parity recalculation for each I/O. RAID 5 is generally considered to be the most versatile RAID level. It works well for file, database, application and web servers.

Figure 4. RAID 5 stripes all drives with data and parity information

Distributed Parity

Data

Blocks

Physical Drives

The capacity of a RAID 5 logical drive equals the smallest physical drive times the number of physical drives, minus one. Hence, a RAID 5 logical drive with four 100 GB physical drives will have a capacity of 300 GB. A RAID 5 logical drive with two 120 GB physical drives and one 100 GB physical drive will have a capacity of 200 GB.

RAID 5 is generally considered to be the most versatile RAID level.

A RAID 5 on SuperTrak consists of 3 to 16 physical drives.

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