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Choosing RAID Controller Hardware: Internal or External?

Today’s servers have impressive storage capability, but that’s only one piece of the puzzle. It’s also critical to be able to access that information quickly when it’s needed and to keep that data protected and safe. That’s where a RAID (redundant array of independent disks) controller comes in. RAID is a collection of disk drives within your system. When used together, these drives provide greater fault tolerance and performance to keep your system operational around the clock.

How RAID Works

A RAID configuration stores a copy of your data on several hard disks to maximize safety, and a RAID controller manages these disks. The controller plays a key role because it brings an extra layer of protection and performance to the system by creating a level of abstraction between the operating system and the physical disks that store the data.

The controller can access multiple copies of data stored on multiple physical devices, but it delivers the disks to the operating system and applications in logical units. In simple terms, this means that even though the information may appear on multiple drives, the server only sees one drive. Not only does that improve performance, it also increases protection in the event of a system crash, as the redundant information stays properly backed up.

Types of RAID Controllers

Knowing which type of controller is best begins with understanding whether an external or internal controller is better for your specific environment. An external RAID controller is, as its name indicates, housed in a high-availability enclosure that is located outside of a host-based server. An internal RAID controller is a card or chip within the computer.

There are five levels of RAID controllers, each with different levels of performance and reliability. Your individual business needs will determine which array is best for your application.

Which RAID Is Right for You?

When trying to decide which type of RAID controller is right for your business, it’s important that you consider the environment where it will be used and your long-term business plans. If your storage needs are going to continue expanding, external RAID may be a good choice because it provides more options for growth. But let’s look at some other considerations.

Internal RAID is best for workstations that don’t have large data-storage requirements and for entry-level servers that don’t have boot-protection requirements. One of the big advantages of using internal RAID is that it is the lowest cost option, as the functionality is already built into the software. The only other cost you’ll need to consider is the cost of additional disk drives. For these reasons, internal RAID software may seem like the best solution for small businesses that have lower storage requirements, but it’s important to get the full picture by understanding the downsides as well. These include:

  • It does not protect or manage data at boot, so if the data is corrupted or the drive fails when the system is booting up, it will not be operable.
  • It puts an additional performance load on the server, and the more complex the RAID configuration, the more of a drain it will have. For that reason, internal RAID is better suited for simple RAID scenarios, such as levels 0, 1 and 10.
  • Because it runs as an application on a computer system, it is vulnerable to viruses.
  • The integrity of the data is affected by system crashes and software or hardware problems.
  • Internal RAID has speed limitations that external RAID does not.
  • If you max out your internal RAID storage, you’ll have to find another solution to continue safeguarding your storage.

For high-performance workstations with large data-storage requirements, external RAID is a far more popular choice. External RAID is also used in servers ranging from entry to enterprise level; the biggest determining factor is the performance and scalability required from the storage subsystem.

The primary hesitation that some have about investing in external RAID is the cost, which is higher than that of internal RAID, but it earns its higher price tag with additional benefits such as:

  • It is protected at boot, so there’s no negative impact on the data if the boot drive fails.
  • The RAID application is independent from the host, so even if the system crashes, the data integrity won’t be compromised.
  • It keeps track of in-progress writes, which means you have greater protection in case of a power loss. That makes it easy to recover from a power loss during a write, which is a protection that internal RAID implementations don’t have.
  • Building and maintaining the array is simple, and it is also easy to migrate and replace when necessary. That means it can easily be replaced or upgraded with a new variant and it is also easier to migrate from one operating system to another.

Weighing Your Options

Choosing between internal and external RAID options will most likely come down to budget allowances and performance needs. The bottom line is that external RAID costs more than internal RAID but also offers better performance and fewer limitations. You’ll have more flexibility in the ways you can use it, more options in the types of configuration for your system and greater flexibility for growth in the years to come.

Additional Resources

To learn more about RAID, please see our blog posts:

To learn more about RAID options and which one is best for your organization, visit us at aventissystems.com or call 1-855-AVENTIS.