Hardware and Software RAID Compared

Hardware and Software RAID ComparedRAID. It's not the stuff you use to kill bugs, but it's definitely a term that you'll come across if you're looking into buying a server. What is RAID? What RAID levels do you need to look for? Where do you start? Sit back, relax, and take a look at what you need to know about RAID.

RAID Defined

Let's start with the simple stuff. RAID stands for: Redundant Array of Inexpensive Disks. Not that exciting, right? That's why it's just called RAID (much more dangerous sounding!). Okay, so what is it?

RAID uses two, and sometimes more, hard disks to ensure fault tolerance (making sure that there's a backup if something goes wrong) or steady performance for a server. Fault tolerance is kind of important, since there's a lot less of a chance that data will be lost or activity will be interrupted if a fault tolerance system is in place. There are two options when it comes to RAID configurations: software RAID and hardware RAID – still with me?

Software RAID

Software RAID is known as the less reliable option, since you can't configure arrays as well as you can with hardware RAID. That said, software RAID is a cost-effective solution that doesn't involve any extra purchases. Software RAID uses partitions on one single disk, which is why this option is cheaper (we'll get to the more complex hardware RAID in a minute).

Downside: if the one disk that you've used to copy data from one drive to another (mirroring), you're doomed. Your data will be gone forever. So, keep that in mind. Software RAID also supports less levels – see below.

Hardware RAID

This is the option chosen by most organizations and businesses, but it's a more expensive choice. Because a business can't afford not to have a fault tolerance in place, the more reliable hardware RAID is the better option.

In order to configure hardware RAID, you have to purchase an additional component called a RAID controller. Controllers, well, control the RAID array. Controllers can be internal or external (though external options tend to be chosen by large organizations due to cost restrictions).

Downside: that added cost can add up. In addition to purchasing a server, you will have to tack on an extra couple of hundred dollars for a hardware RAID controller card.

Hardware and Software RAID Compared: Choice, Choices, Choices

Not only do you have to choose hardware or software RAID, but you'll also have to decide on a RAID level (what? there's more to this? keep reading!). A RAID level relates to how you plan to configure RAID.

The way to pick a RAID level is to determine if you are going to use RAID for fault tolerance, performance, or both. If you go the hardware RAID route, you'll have to also consider the type of controller that you have purchased (not all controllers support all levels, so keep this in mind as you shop for a controller).

RAID levels include 0, 1, 5, and 10 with 10 being a combination of levels 1 and 0. Level 5 is the most common level used by businesses because it provides the best fault tolerance and performance. In between 0,1,5,and 10 are various other levels (2,3,4,and 7), though those levels are a lot more specific.

The basic rule of thumb regarding RAID levels is this (and there are, of course, exceptions): home users will be happy with level 1, and most businesses will be content with level 5.

One last thing to remember: RAID helps with it comes to backing up data, but it is not the only method of backup that you should have in mind.

Got more RAID questions? Need more explanations? Just ask!

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