RAID offers many advantages over the use of single hard disks, but it is clearly not
for everyone. The potential for increased capacity, performance and reliability are
attractive, but they come with real costs. Nothing in life is free. In this section I take
an overview look at RAID, to help explain its benefits, costs, tradeoffs and limitations.
This should give you a better idea if RAID is for you, and help you to understand what
RAID can do--and what it can't do.
As you read on, it's essential to keep in mind that with RAID, it's definitely the case
that "the devil is in the details". Most common blanket statements made about
RAID like "RAID improves availability" or "RAID is for companies that need
fast database service" or "RAID level 5 is better than RAID level 0" are
only true at best part of the time. In almost every case, it depends. Usually,
what RAID is and what it does for you depends on what type you choose and how you
implement and manage it. For example, for some applications RAID 5 is better than
RAID 0; for others, RAID 0 is vastly superior to RAID 5! There are situations where a RAID
design, hardware and software that would normally result in high reliability could result
instead in disaster if they are not properly controlled.
Next: RAID Benefits
