In the past, RAID arrays have been largely controlled by a RAID controller expansion card. Today, many modern motherboards include built-in support for some types of storage arrays. The questions are, what is a RAID controller, exactly, and when do I need a RAID controller?
Benefits of RAID
RAID, or Redundant Array of Independent Disks, allows you to use 2 or more drives to create an array, which is recognized as a single storage location by your computer. One of the primary advantages of a RAID array is data security, thanks to the storing of duplicate copies of your data on multiple drives (known as mirroring).
Speed is another advantage, which is the result of writing and then reading data from multiple drives at once, taking advantage of the maximum data transfer rate of each drive in a process known as data striping.
What are the most commonly used RAID modes?
Many of our industrial and embedded customers utilize RAID arrays in their projects in order to protect important data and enhance the operational speed of equipment that depends on information being read from and written to hard disks. While there are many forms of RAID involving differing numbers of disks and various combinations of features, the vast majority of the questions we receive involve the three simplest modes:
RAID 0 – Often referred to as striping and generally utilized to increase operational speed, RAID 0 writes alternating sections of your data to multiple drives. Because you’re able to read and write data from multiple disks at the same time, there is the potential for significantly increased data handling speeds. However, one downside of having a two-disk RAID 0 setup is that if one disk fails, all data is lost since no one disk holds all of the information.
With RAID 0, the total amount of usable space is the sum of the capacity of all the disks in the volume. For example, if you have four 2TB drives, then the total capacity of the volume would be 8TB.
RAID 1 – Generally referred to as mirroring and primarily employed for enhanced data security, RAID 1 is what most users think of when they’re considering implementing a RAID array. RAID 1 writes a duplicate copy of your data to multiple drives, giving you the peace of mind in knowing that even if one drive fails, you still have a backup copy of your information. Many systems intended for use in storage arrays include hot-swap bays which allow for disks to be replaced while the system is still in use.
The total usable space in a RAID 1 volume is a single disk, since the same data is being written to all the drives in the volume. The value for using more than just 2 disks for RAID 1 is that each drive added to the volume is another copy of the data. For example, if you have a RAID 1 volume of four 2TB disks, then 2TB of usable space is available, with 3 copies of the data being written to the other disks, allowing for up to 3 drive failures before data is lost.
RAID 10 (1+0) – A combination of the best features of both RAID 0 and RAID 1, this array setup requires the use of at least four drives to stripe data across multiple drives while simultaneously duplicating that same information to additional drives. In this setup, you receive the speed bonuses of RAID 0 and the data redundancy advantages of RAID 1. Since everything in RAID 10 is mirrored, the amount of total usable space will be half the total capacity of the disks in the array. For example, if you have four 2TB disks, the total amount of usable space available would be 4TB.
Check out our blog What is RAID for more detailed information about the types of RAID.
What modes does on-board RAID support?
The complexity of a supported RAID setup will depend on the particular motherboard you’re using. In general, most boards that support RAID will be able to handle some form of RAID 0 or 1, with many fully capable of controlling a 0+1 array. Of course, a dedicated controller will likely come packaged with more advanced features and capabilities to allow for more intricate control of array settings. However, for the majority of users interested in achieving moderate performance speed increases or basic data redundancy, those goals can often be achieved with the RAID functionality built into many of today’s motherboards.
What is a RAID controller?
A RAID controller (also commonly referred to as a RAID controller card) is hardware like a card or chip that manages the hard disk drives (HDDs) or solid-state drives (SSDs) in a computer or RAID array to leverage the benefits of RAID. It’s important to understand your system’s capabilities because not every RAID setup needs a RAID controller card.
When should you consider an add-on RAID controller?
Even with the enhanced on-board capabilities of modern systems, there are still a number of instances where a dedicated controller is a sound investment. The most obvious situation stems from the fact that not all motherboards support on-board RAID. If you need to set up data redundancy or stiping on a legacy system, installing a RAID controller card is a simple procedure that can get you up and running quickly.
At OnLogic, we occasionally work with customers who are interested in implementing more complex array setups involving multiple hard drives in various RAID configurations. When executing the other forms of RAID (additional modes may stripe data at the bit or byte level paired with duplication), we often recommend a dedicated controller to ensure proper implementation and allow for more exact control over array setup and maintenance.
Every redundant array application will have its own variables and requirements. The best way to determine if the included RAID functionality of a system will be sufficient for your needs is to speak with one of our technical sales experts. If you’re considering a RAID setup for your industrial application, or have questions about how RAID could benefit your business, contact us today.
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Darek is the Communications Manager at OnLogic. His passion for both journalism and technology has led him from the newsrooms of local papers to the manufacturing floor of IBM. His background in news gathering has him always on the lookout for the latest in emerging tech and the best ways to share that information with readers. In addition to his affinity for words, Darek is a music lover, juggler and huge fan of terrible jokes.