RAID 5

 

RAID 5 includes disk striping at the byte level and parity. In RAID 5, the parity information is

 

written to several drives. RAID 5 is best suited for networks that perform a lot of small I/O

 

transactions simultaneously.

 

RAID 5 addresses the bottleneck issue for random I/O operations. Since each drive contains both

 

data and parity numerous writes can take place concurrently. In addition, robust caching algorithms

 

and hardware based exclusive-or assist make RAID 5 performance exceptional in many different

 

environments.

Uses

RAID 5 provides high data throughput, especially for large

 

files. Use RAID 5 for transaction processing applications

 

because each drive can read and write independently. If a

 

drive fails, MegaRAID uses distributed parity to recreate all

 

missing information. Use also for office automation and

 

online customer service that requires fault tolerance. Use for

 

any application that has high read request rates but low

 

write request rates.

Strong Points

Provides data redundancy and good performance in most

 

environments

Weak Points

Disk drive performance will be reduced if a drive is being

 

rebuilt. Environments with few processes do not perform as

 

well because the RAID overhead is not offset by the

 

performance gains in handling simultaneous processes.

Drives

Three to 32

Chapter 3 RAID Levels

21