The terms SATA and RAID are often confused as being the same basic thing. While both are ways that data can be transferred between a storage device and a computer, they have some inherent differences. Most hard drives sold on the market today are serial (SATA) or Parallel (PATA) drives.
Hard drives are not sold as being RAID hard drives because any hard drive (PATA or SATA) can be used with a properly equipped RAID controller. SATA (and PATA) hard drives connect to a computer motherboard as single, unique entities. If an SATA hard drive is plugged into a computer by default it will appear as a new storage device that data can be written to. A RAID controller takes those individual SATA or PATA hard drives and slaves them together to accomplish any of several different configuration goals.
The Difference Between SATA and RAID- A Simple Analogy
Think of individual SATA hard drives as being individual strings of Christmas lights. They can be plugged individually into a wall socket (like SATA hard drives being plugged into a computer motherboard) and will work just fine but look rather boring.
However, using a special controller box (the RAID controller in this example) many different strings of lights can be hooked together and controlled in ways that make them do things that they could not do by themselves. They can flash in sequence, they can turn on and off in chunks, or even appear to dance as individual strings are turned on and off in interesting patterns. This ability to take individual drives and turn them into something more robust is what makes RAID arrays so powerful and useful in specific situations.
RAID controllers sit between the computer motherboard and the hard drive. Instead of plugging the hard drives into the motherboard the user connects them to special ports in the RAID card which is usually plugged into an available PCI slot on the motherboard. Be aware that many modern computer motherboards come with RAID capability built in. On these motherboards it is no longer necessary to purchase an add-on RAID controller as many computers can activate a basic RAID array through the computer’s BIOS setup screens. But what exactly does a RAID array do with the SATA drives attached to it?
Understanding RAID Arrays
Take for example a system with two hard drives installed in it. If the system does not use a RAID controller those two drives will appear as two separate drives each with its own dedicated amount of storage space. However, if those same two hard drives are connected to the computer’s RAID controller they will show up as only one hard drive with a capacity that varies depending on how the RAID is configured.
Depending on how the user sets up the RAID array the two hard drives can be configured to increase data transfer rates (useful for video editing and other high bandwidth applications) or configured to provide a redundant, real time backup. The two most common and most simple modes that a RAID array can function in are shown below:
RAID 0 – A setup where multiple hard drives are combined together to make one large drive. in a RAID 0 array data is cut into chunks and “striped” between the two or more hard drives. This can greatly increase transfer speed but has more risks associated with it since if one drive fails the data on the other drives is worthless as well.
RAID 1 – A simple mirroring arrangement where both drives are exact copies of one another. A RAID 1 array requires the use of two identical size hard drives. If one drive fails in some way the second drive acts as a backup.
There are additional RAID setups that provide both speed and backup capabilities but most require additional hard drives to be installed on the system and are intended for enterprise level applications.
For the home user an SATA based RAID 0 setup is a good idea in certain situations such as if the user will be doing a lot of video editing or high bandwidth gaming. For most users however a RAID 1 setup provides the best backup option and should be considered if equipment and power requirements inside the computer allow for it.