What Is RAID? Understanding the Technology Behind Data Protection

Much to my dissatisfaction, I will not be talking about my favorite insecticide product in this article. Instead, today’s central topic is Redundant Array of Independent Disks, or RAID, as most of us know it.

As opposed to killing bugs (even computer ones):

RAID refers to data storage technology that spreads and duplicates data across multiple drives to protect it from potential drive failure or to increase the speed of reading and writing to a hard disk.

In essence, a RAID array can write data faster by using more than one disk (striping), or it can write data to multiple disks (mirroring) for backup purposes — it can do both of these things with even more disks.

As you can probably imagine, this makes RAID incredibly important and useful in keeping your data safe and making it really fast when saving and loading. Therefore, you’ll commonly find it used by enterprises and people who place a premium on protecting valuable information.

RAID distributes data in different ways, depending on the “level” of RAID you choose. Here’s a quick rundown of the concept’s history and standard methodology to give you an idea of what’s happening behind the screens (pun intended).

History and Development

The I in RAID initially stood for ‘inexpensive,’ as David Patterson, Garth Gibson, and Randy Katz coined the term in 1987. Their 1988 paper “A Case for Redundant Arrays of Inexpensive Disks (RAID)” created common terminology (RAID levels being the most popular) for the technologies that were already in use (adding the name to a face kind of thing).

However, industry vendors didn’t like the low-cost implication, so they changed the I to ‘independent’. You see, hard drives were very expensive back then, making efficient data storage a major concern. This was also a time when large mainframe computers dominated the computing landscape, though this dynamic began to shift with the rise of personal computers.

Their emergence gave birth to the idea of RAID in which a bunch of cheaper drives together make for something better, outperforming the high-end disk drives found in mainframes. Although using numerous drives increased the potential for failure, the inherent redundancy would ensure that everything could keep working even if one drive died, surpassing that of any individual mainframe drive.

Types of RAID Levels

The various levels of RAID differ in the way they achieve trade-offs between performance, redundancy, and storage capacity. Initially consisting of five levels, a more modern categorization goes by three groups:

• Standard: RAID 0, RAID 1, RAID 2, RAID 3, RAID 4, RAID 5, RAID 6
• Nested: RAID 10, RAID 03
• Non-Standard: RAID 7, Adaptive RAID

Let’s take a closer look at the most common levels and what each represents.

RAID 1

A more elaborate configuration, RAID 1 is all about making copies of your data for safety.

In the event of disk failure, you still have access to your data as long as one disk is up and running. This method also doubles the read efficiency of one drive since it allows reading from any disk in the array.

However, RAID 1 is not the fastest way to save information because you need to write data on both drives, and you only get to use the storage space of one drive. As such, it’s frequently used in instances that require constant uptime and fast read speeds, like email servers.

RAID 6

Building upon RAID 5’s functionality, RAID 6 offers greater fault tolerance. Often referred to as double-parity RAID, it requires a minimum of four drives.

RAID 6 similarly distributes data across the array, with the addition of more information. This crucial layer of redundancy features two sets of parity information instead of just one, dispersed among the disks for higher data protection.

RAID 6 can survive two simultaneous drive failures without data loss. But, calculating and writing double parity information takes more time, leading to slower write speeds than RAID 5. Since it acts as a buffer against potential hardware issues, RAID 6 is a strong contender for long-term, reliable storage of important data, especially large datasets.

RAID creates a single logical storage unit by combining multiple physical disks. This is achieved through various hardware and software — all of which I’ll go through in the next few minutes.

Striping, Mirroring, and Parity

Data striping is a technique used to split data between disks into smaller chunks or stripes, as they are called. Instead of saving the entire file on one hard drive, you break it into smaller pieces and spread those pieces across multiple hard drives.

This allows the system to read or write to several stripes simultaneously across different disks, significantly boosting performance as opposed to using a single disk.

On the other hand, data mirroring replicates identical data onto multiple disks, creating a mirrored copy on each. If one of the mirrored disks fails, the system can seamlessly continue using the data on the healthy drive, ensuring high availability and protection from single-disk failures.

Then, there is parity calculation. Without going down the rabbit hole in explaining parity since it requires knowledge of binary and the logical XOR (Exclusive OR) expression, let’s just say it’s a way to check for and fix data inconsistencies caused by a failing disk. It’s much like having a cheat code that helps you recover your information.

Do note that the number of recoverable disk failures depends on the specific RAID level. For instance, RAID 5 can handle a single disk failure using parity, while RAID 6 offers protection against double disk failures with the help of dual parity calculations.

RAID Controllers

Moving on to the hardware side, a RAID controller is a bridge of sorts between physical drives in a storage array and the operating system. It directs data to the right hard drives and handles all the complicated stuff, making sure everything is backed up and running smoothly if a hard drive malfunctions.

For the most part, RAID controllers are dedicated cards equipped with a processor and cache to manage all RAID operations independently. This offloads the work from the CPU, potentially leading to better performance. Additionally, hardware RAID controllers often permit booting the operating system directly from the RAID volume.

I specifically mentioned the hardware part twice because RAID controllers can also be software-based. The general idea is the same, only done differently by leveraging the computer’s CPU and system memory to manage the RAID array. While generally more cost-effective than their hardware counterparts, software RAID controllers can strain system resources and may not be as reliable as a dedicated card.

Hot Swapping and Hot Spares

Imagine one of your hard drives is starting to act up. That’s where hot swapping and hot spares come in with replacements before complete breakdown. Hot swapping enables drive removal and replacement without interrupting system operations or RAID performance.

To successfully perform it, you’ll need a special hot-pluggable interface like SATA or SAS (kinda like changing a tire while the car is still running). A hot spare acts as a pre-configured reserve drive (akin to a spare tire). It is ready to take over for a failing component within the array.

In other words, it’s an extra disk connected to the RAID controller, and it remains inactive until the you-know-what hits the fan. It can then automatically or manually (depending on configuration) take over for a failed drive, resulting in a swift restoration of the RAID’s redundancy level.

All the cool stuff RAID does varies depending on the chosen RAID level. Here are the top advantages:

Data Redundancy

Arguably the biggest benefit, RAID makes sure your data doesn’t disappear if something bad happens to one of your drives.

In RAID 1, each bit of data has an exact copy on another drive. In RAID 5 and 6, data is striped across drives, and extra parity information is stored to help put everything back together if a drive fault occurs.

With redundancy, data remains intact and accessible even in the worst-case scenario as it’s possible to rebuild the data from the remaining drives.

Improved Performance

Though not quite boosting the processing power like some tech from Intel and AMD, RAID does its darnedest to enhance read/write speeds for certain configurations through the simultaneous execution of many read/write operations.

RAID 0 allows the system to read/write data in parallel, effectively multiplying transfer speeds.

RAID 10 combines striping with mirroring to get the best from both techniques, making it ideal for applications that require speed and data protection.

Scalability

In the world of ever-growing data needs, RAID opens the door to scalable storage expansion by adding more drives to the array. Certain configurations like 5 and 6 make the process of increasing the total storage capacity easy.

When you take into account that this can be done without downtime or hassle, RAID systems are rather handy for organizations aiming to scale their on-premise data infrastructure.

As a bonus, RAID is compatible with a broad range of devices, which means servers, workstations, and even personal PCs can be covered.

Fault Tolerance

Having more hard drives is great, but it also means a greater risk of failures. And that’s where fault tolerance comes into play. It builds upon data redundancy as RAID 5 and 6 can tolerate the failure of a single drive within the array without data loss.

In such a scenario, the RAID controller uses the parity information to rebuild the data on the failed drive from the remaining functional drives.

Hence, fault tolerance allows the system to stay operational through thick and thin, minimizing downtime and data loss risk — music to every business owner’s ears.

If you’re intent on exploring RAID’s possibilities, I’m pleased to say that setting it up is fairly straightforward.

Choosing the Right RAID Level

The RAID level you choose will lay the foundation for your RAID system.

Intended performance, degree of redundancy, and cost will be three key factors you’ll need to consider to get the most bang for your buck.

Ideally, you want to be on a first-name basis with your hardware and everything that goes into your storage infrastructure. If configured properly, RAID supplies an easy way to beef up redundancy and speed.

With that in mind:

• RAID 5 or 6 are the top candidates with their balance of redundancy and capacity for storing large datasets in enterprise environments.
• RAID 1 is a decent option for secure backups.
• RAID 0 can provide a performance boost for gamers who rely on fast loading times.
• For a balance of performance and redundancy for critical data, RAID 10 might be the best fit.

If none of the above fulfill your needs, you can always try a proprietary setup that incorporates your unique configuration — a sort-of niche RAID, if you will.

Setting Up RAID

The configuration process will vary depending on your system setup. For Windows 10 and 11 users, here’s a general guideline for RAID 5:

1. Click on the Windows Start button and choose “Settings”
2. Go to “System”
3. In the left sidebar, select “Storage”
4. Under the More Storage Settings section (‘Advanced Storage Settings in Windows 11), select “Manage Storage Spaces” (just Storage Space in Win 11)
5. In the new window, click the Create a new pool and storage space link (“Add a new Storage Pool” in Windows 11)
6. Select the drives you want to pool and click “Create pool”
7. Write the name and drive letter heading
8. Under the Resiliency section, click the resiliency type drop-down and select “Parity”
9. Under “Size,” write down your desired capacity and size settings
10. Hit the Create storage space button to activate the array

To aid you in your raid for more redundant storage (excuse the poor wordplay), you can also use the Disk Management tool — an older method that still does the trick.

Migrating to RAID

Your first course of action should be to back up your data to an external location (the cloud is a popular choice). You have various tools and methods for the job, from RAID controllers that offer migration capabilities to software like Windows Backup and Restore, Acronis Cyber Protect Home Office, and Linux rsync command — depending on your OS, RAID level, and backup frequency.

To perform the migration, give EaseUS Partition Master, Intel Rapid Storage Technology, or some other platform a go. Let it do its thing for a while — monitor the progress but refrain from making interruptions as large datasets take a few hours at the most.

Afterward, thoroughly verify the data to make sure it is transferred correctly. Perform file system checks and data comparisons with the original backup.

The ideal RAID setup hinges on your environment, but the good news is that it’s rather convenient across the board.

RAID In Homes and Small Businesses

Both private users and budding businesses can revel in all the big benefits of RAID, though the focus is primarily (or should be, at least) on data protection and redundancy, as opposed to improved performance. Since typical personal use cases include media storage and backup, the standard recommended RAID setup is RAID 1.

It’s simple to configure and keeps valuable data like financial documents or family photos safe by duplicating data on multiple drives.

Small businesses, for which file redundancy is essential, can also use this setup. However, they might be more inclined to set up RAID 5 or 6 if they’re looking for equal measures of redundancy and capacity for storing business documents. This protects against a single drive failure while offering more storage space than RAID 1.

Enterprise RAID Solutions

Among the more popular RAID configurations for enterprise storage is RAID 10, though advanced variants like RAID 50 (RAID 5+0) and RAID 60 (RAID 6+0) are getting in on the action. Depending on the enterprise’s needs, these can tilt more toward high performance, high redundancy, or cost-effectiveness.

As an unofficial rule of thumb, enterprise RAID configurations tend to be integrated with SAN, usually RAID 1 and RAID 10 for critical data storage and RAID 50 or RAID 60 for a mix of performance and file redundancy.

Don’t be surprised to see NAS devices using RAID 1 for simple redundancy (both are disk arrays, after all) or RAID 10 for higher performance and redundancy. NAS with RAID 5 or RAID 6, on the other hand, provides a good measure of storage efficiency and fault tolerance.

Cloud and Virtualized Environments

RAID lies at the very foundation of all the essential features every respectable cloud storage solution offers — efficient and reliable operations, maintaining data integrity, and offering diverse storage needs.

Look no further than virtual machines (VMs) that use virtual disks stored on RAID-configured storage arrays. The hypervisor (software that creates and runs VMs) manages these virtual disks and presents them to VMs as if they were physical disks.

Thanks to this wizardry, VMs can run independently of the underlying hardware, enabling you to easily change how you use the available resources.

RAID’s well-documented impact on performance is especially beneficial when you want to make your VMs really fast, more so when they need to handle lots of data at once.

Virtualized environments often host multiple VMs running diverse workloads, which means workload variability plays a key role in consistent and reliable performance.

Just like any other technology, keeping your RAID system fit as a fiddle calls for proper maintenance and attention to issues that can suddenly creep up.

Monitoring RAID Arrays

Your best bet here is to invest in a monitoring tool that will provide proactive maintenance and also optimize performance and resource allocation, to name a few benefits. In that regard, platforms like ManageEngine OpManager, Nagios XI, and Site24x7 will prove valuable allies. You can also check the BIOS or UEFI settings or built-in OS tools for basic RAID monitoring options.

In no way does that absolve you from creating a maintenance hygiene routine and sticking to it. Regularly check your RAID controller’s logs or system event logs for warnings or errors. Keep an eye on the S.M.A.R.T. status of your drives to identify potential drive issues before they wreak havoc and, of course — have a backup strategy in place.

Dealing with Drive Failures

First, find the culprit, AKA failed drive within the array, via the RAID monitoring tool of your choice (system alerts may help). If your system supports hot swapping, your job will be easier. If not, power down the system safely and make the replacement.

Once again, this is when regular backups and disaster recovery planning pay dividends — don’t skimp out on these. Data recovery can get complex and expensive fast, not to mention impossible at times.

RAID Rebuild and Recovery

The RAID controller uses the remaining functional drives and parity information (in RAID 5 or 6) to reconstruct the data onto the new drive.

This rebuild process can take several hours to days depending on the size of the drives, the RAID level, and the speed of your system.

Do what the pros do and minimize or downright avoid writes to the array during the rebuild to prevent stressing the system.

You should know: For more intricate scenarios involving multiple drive failures or corruption exceeding RAID’s capabilities, data recovery software becomes necessary. Choose software compatible with your specific RAID configuration to effectively reconstruct RAID arrays, recover lost configurations, and salvage data from damaged disks within the array.

Keeping up with growing data storage demands ain’t easy, but certain tech is making notable strides.

Technological Advancements

If you thought AI was going to be involved in some way, you thought correctly. Its integration within RAID controllers means we’re ushering in an era of intelligent controllers that analyze how you access particular data and automatically adjust RAID parameters based on your specific needs.

Much of the innovation is (and will likely continue to be) honed in on data security. I’m already seeing early-bird RAID solutions that integrate encryption at the RAID level, amplifying protection without sacrificing performance.

Alternatives to Traditional RAID

As concepts that are gaining traction, software-defined storage (SDS) and software-defined RAID (SDR) represent the new kids on the block.

• Software-defined storage: SDS deals in data disaggregation, treating storage as a pool of virtualized resources by breaking down data into detailed sub-categories. This offers greater flexibility and scalability as storage can be easily added or removed from the pool. Its price tag is another boon since it’s a more cost-effective option compared to dedicated RAID controllers.

• Software-defined RAID: SDR is kind of like adding another layer to all of that, using software to manage your RAID setup instead of those special cards. Benefits are very similar to hardware RAID, though there is more flexibility since these RAID configurations can be easily modified or migrated.

As time goes on, I’m betting we’ll see even more alternatives to traditional RAID.

Get this — RAID is getting even faster these days. On top of the list of emerging trends is NVMe RAID, taking advantage of high-speed drives to create RAID arrays with significantly speedier read/write operations versus traditional HDD-based iterations.

This is particularly useful for applications requiring real-time data processing or high-performance computing (which is every other one made today, it seems).

With cloud storage taking a bigger piece of the storage pie, some vendors are toying with RAID configurations as a service, allowing you to leverage the benefits of RAID without managing physical hardware.

A cloud-based RAID is best suited for scalable and remotely accessible storage solutions, especially since data can be distributed across multiple clouds and in different regions. Whatever solution you choose, RAID is an essential technology for protecting your data that you don’t want to lose.