Types Of RAID

Basically there are two types of RAID implementation :
• Software RAID :
RAID functionality is provided by the OS itself.
OS overhead is high.
System Performance is slow.
Low priced solution.
• Hardware RAID :
Separate hardware is there to provide RAID functionality.
Very low OS overhead.
High performance.
Implementation cost higher.


Software RAID A Bit In Detail

•Software RAID can be implemented from NOS like WinNT, Win2K , SCO OSR ,Linux etc.

• In this type of implementation all RAID functionalities are taken care by the host CPU which ultimately tax upon the CPUs ability to perform other computations.
This is pretty low cost solution. Practically customer does not need to buy anything (hardware or software) extra (except for the required HDD). The basic OS can do this functionality

•Software RAID is “Pseudo RAID”. It does not support all basic RAID functionalities & levels.

• It does not require any extra hardware and even can work over IDE interface.

• This is not an OS independent solution. Thus OS structure and limitations plays a major role in its capability.

Software RAID is NOT Valid solution for high Mission critical and high performance Servers


Hardware RAID In Detail

•Hardware RAID requires a RAID controller.

•In this type of implementation all RAID functionalities are taken care by the RAID CPU which offloads the host CPUs transaction with HDDs to a great extent (nearly 90%).

•This is a priced solution…..what I mean, one need to buy a RAID card extra to have better fault- tolerance, availability and performance of the Server system. Better the features, higher the price is ...

•Hardware RAID is “Real RAID”. It supports all basic RAID functionalities and levels.

•Performance is very high, since RAID CPU offloads host CPU.

•This is an OS independent solution. Thus OS structure and limitations does not play any role in its capability.

•It gives a connectivity benefits of SCSI as well.

•More robust fault-tolerant when compared with Software RAID.


Hardware RAID is THE SOLUTION for Mission critical and High performance servers.