Tech Minutes

RAID in Plain English

RAID, you hear it everywhere. From the techs in the server room talking about it to computer manufacturers asking if you want a RAID formation for your computer's hard drive. Not all RAID configurations are considered equal. Here's an explanation of RAID formats in plain English.

RAID stands for Redundant Array of Independent Disks. RAID is a way of storing the same data in different places on multiple hard drives. By spreading out the distribution of data on multiple disks, it improves performance. Not only this, but it also increases the computer's ability to keep running in case one of the hard drives fails.

A RAID array appears to the operating system to be a single hard disk since the multiple disks are moving in sync with each other. To do this, RAID employs a technique called disk striping. Disk striping is when the computer takes data and spreads it across evenly among the hard drives. These "stripes" can range in size depending on how many users use the RAID array and how large the files are.

I will be going over the two most common RAID arrays, however, there are around nine different RAID types. Each of the RAID arrays strikes a different balance between performance and reliability and is denoted as RAID-X where X is a number.

To begin with, RAID-0 is a RAID array where the drives have striping over the hard drives but there is no redundancy of data, which means there is no backup so if one drive fails then all drives will fail. This RAID array offers improved performance and additional storage. While the performance and additional storage is great, the risk of failure increases with more disks in the array, so at a minimum catastrophic data loss is almost twice as likely when compared to non-RAID drives. It is highly suggested not doing this RAID array unless you are confident in your backup solution, as the risk of data loss doubles since if one drive fails it could prevent you from accessing your data.

Continuing on, RAID-1 is a RAID array where the data is written identically to multiple hard drives, otherwise known as a "mirrored set." While any number of disks may be used, most implementations of RAID-1 deal with only two hard drives. The RAID array continues to run as long as at least one drive is functioning. With RAID-1 the speed in which your computer reads the data on the hard drive is improved since either disk can be read at the same time, however, Write performance (how fast your computer stores data onto the hard drive) is the same as non-RAID hard drives. RAID-1 is the perfect balance of performance and protection from data loss due to hard drive failure.

Of course, things get more complicated when adding more hard drives to the configuration, but the biggest thing to consider is keeping your data redundant, so be sure to have a good backup solution that you can test regularly, regardless how many drives are arrayed together inside your PC/server.

Chris is a Trusted I.T. Advisor, Computer Fanatic, Web, Graphics & Software Designer. He's also an Amateur Photographer and Filmmaker. Chris lives with his wife Charlotte and their 2 sons in Upstate NY.


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