Comparing Intel Hardware and Software RAID solutions

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Feature Guide

Fault Tolerance

While both software RAID and hardware RAID can tolerate a hard

drive failure, only hardware RAID can tolerate a server failure or

operating system crash. If a server fails or OS crashes, hardware

RAID controllers can protect any data left in the cache with the

use of an optional battery backup. When server operation is

resumed, the HW RAID controller will ﬁnish its disk operations.

Unlike HW RAID, software RAID caches its data in the main system

memory. Since this memory is not battery backed, data may be

corrupted when a server fails or the OS crashes. Some other fault

tolerant features that only apply to Hardware RAID are advanced

media error detection and correction with Patrol Read and isolation

of failing hard drives so that they are not reused.

Troubleshooting Capabilities

Hardware RAID provides better capabilities for problem diagnosis

and prevention. With software RAID, there is limited detail in event

ogs if there is an issue or failure. The information that is provided

is only available after the OS boots and may be lost completely if

the system or OS crashes. With hardware RAID, events are logged

directly into memory on the RAID controller and the detail is much

more comprehensive. Event logging is also available before the

OS boots and is preserved after a system or OS crash.

Intel offers several types of RAID solutions, ranging from

software RAID (aka “host-based RAID”) that resides on Intel®

Server Boards to add-in hardware RAID controllers powered

by LSI MegaRAID* technology. There are signiﬁcant

architectural differences between these software and

hardware RAID solutions that ultimately affect fault tolerance,

performance, troubleshooting and price.*

Some of the main architectural differences between software

and hardware RAID are:

While software RAID has its place in low-cost storage

solutions that require basic reliability, hardware RAID is the

preferred solution for applications that require high reliability

and availability.

Comparing Intel® Hardware and

Software RAID solutions

Software RAID

RAID processing performed by

host server’s CPU

Manages RAID subsystem at

operating system level

Uses host system memory

No dedicated battery backup

Hardware RAID

RAID processing performed by

dedicated CPU on RAID controller

Manages RAID subsystem

independent from host

Dedicated cache memory

on controller

Dedicated battery backup

Summary of content (2 pages)

PAGE 1
Feature Guide Comparing Intel® Hardware and Software RAID solutions Intel offers several types of RAID solutions, ranging from Fault Tolerance software RAID (aka “host-based RAID”) that resides on Intel® While both software RAID and hardware RAID can tolerate a hard Server Boards to add-in hardware RAID controllers powered drive failure, only hardware RAID can tolerate a server failure or by LSI MegaRAID* technology. There are significant operating system crash.
PAGE 2
Performance Advanced Feature Set In the past, a primary reason not to use software RAID was The firmware existing on hardware RAID allows for advanced algorithms that are not easily made available for software because it impacted the overall system performance since it RAID. These features include RAID 6, revertible hot-spare, advanced array migration or capacity expansion, and higher requires the additional CPU cycles to perform RAID physical device limits.