Data Safety Vs. Performance
While RAID setups for servers are created to protect data against hardware failure, home users primarily focus on the possible performance gain. While a RAID 3 or RAID 5 setup provides excellent fault-tolerance together with pretty fast transfer rates and access, it is quite expensive to implement: first, you require at least three SCSI hard drives (usually, 5 or 6 are used). Second, these types of controllers are some the most expensive hardware you can buy.
The high price in itself explains why RAID modes 3 and 5 have not been accepted in the mass market. Home users usually won't buy half a dozen hard drives and a $500 controller merely for the purpose of speeding up their disk subsystem. Instead, RAID 0 and 1 have become the popular modes that the majority of users implement.
As you will see later, using a four-drive instead of a two-drive stripeset does not increase transfer performance by much, but this makes sure that the minimum transfer speeds remain impressively high throughout the whole medium.
On-Board RAID Vs. PCI Cards
There are several motherboards available that come with an additional IDE controller, usually an IDE RAID chip. Most of them are HighPoint chips, some are Promise chips and very few are AMI's controllers (e.g. IWill). The main reason why such controllers are integrated directly onto motherboards? Price. On-board RAID gives motherboards an excellent added-value feature while not adding much to the overall board price tag.
PCI IDE RAID controllers start at approximately $60. Retail kits such as the ones we tested from AMI and Promise are more expensive, but they come with two 80-pin IDE cables, comprehensive manuals and sometimes additonal management software or other add-ons.
Software Or Hardware RAID?
A few weeks ago, we touched upon the topic of software RAID, using the RAID capabilities of Microsoft Windows 2000 as an example. On the one hand, a software array is more flexible, as you can use almost every drive that is accessible by Windows. On the other hand rescuing the data can be more problematic if either Windows 2000 or one of the drives crashes - so the data safety issue is something that you should think about twice. Here's the link to our Software RAID article:
RAID Without Additional Hardware: Do It Yourself With Windows 2000
