When you’re designing a rugged computing system—whether it’s headed into a defense environment, an industrial facility, or an edge deployment—storage is rarely an afterthought. Data has to be fast, reliable, and available when it matters most. That’s where RAID comes in.
RAID (Redundant Array of Independent Disks) has been a cornerstone of reliable storage design for decades. It allows multiple drives to work together as a single system, helping you balance performance, capacity, and fault tolerance. In this guide, we’ll walk through what RAID is, how the most common RAID levels work, and how to decide which configuration makes the most sense for your application.
What Is RAID?
RAID stands for Redundant Array of Independent Disks. The idea goes back to the late 1980s, when researchers at UC Berkeley were looking for better ways to improve storage reliability and performance without relying on a single, expensive drive.
Instead of putting all your data on one disk, RAID spreads it across multiple drives and manages how that data is written and protected. Depending on how it’s set up, RAID can make storage faster, more resilient, or both. These setups are called RAID levels, and each one handles data a little differently.
The Building Blocks of RAID
All RAID levels are built from a few simple concepts:
- Striping spreads data across multiple drives to improve performance.
- Mirroring writes the same data to more than one drive, so there’s a backup if something fails.
- Parity uses math to rebuild data if a drive goes down.
Every RAID level is just a different mix of these ideas. That mix determines how fast the system is, how much usable storage you get, and how well it can handle drive failures.
RAID Levels Explained
RAID 0 — All About Speed
Best for: Temporary data, scratch space, high-speed processing
Minimum drives: 2
RAID 0 is the simplest setup. Data is striped across multiple drives, which means reads and writes happen in parallel. The result is excellent performance.
The tradeoff? There’s no safety net. If one drive fails, everything is lost. RAID 0 is best used when performance is the top priority and the data itself isn’t critical—or is protected somewhere else.
- Fault tolerance: None
- Performance: Very fast
- Usable capacity: 100%
RAID 1 — Straightforward and Reliable
Best for: Boot drives, critical system data, small databases
Minimum drives: 2
RAID 1 mirrors data between two drives. Every piece of data is written twice, so if one drive fails, the system keeps running without missing a beat.
It’s simple, proven, and dependable. While it doesn’t boost write performance, read speeds can improve slightly, and recovery is quick and painless.
- Fault tolerance: One drive can fail
- Performance: Solid, predictable
- Usable capacity: About 50%
RAID 5 — A Practical Middle Ground
Best for: File servers and shared storage
Minimum drives: 3
RAID 5 balances efficiency and protection. It stripes data across drives and adds parity information, which allows the system to recover if a single drive fails.
Read performance is strong, and storage efficiency is good. Writes are slower due to parity calculations and rebuilds can put extra stress on remaining drives—especially with larger disks.
- Fault tolerance: One drive failure
- Performance: Strong reads, moderate writes
- Usable capacity: One drive’s worth used for parity
RAID 6 — Extra Insurance for Bigger Systems
Best for: Large arrays and high-capacity drives
Minimum drives: 4
RAID 6 works much like RAID 5, but with an added layer of protection. It uses double parity, allowing the system to survive two drive failures at the same time.
This is especially important with today’s large-capacity drives, where rebuilds can take a long time. The added safety comes at the cost of slower write performance, but for many environments, the tradeoff is worth it.
- Fault tolerance: Two drive failures
- Performance: Excellent reads, slower writes
- Usable capacity: Two drives reserved for parity
RAID 10 — Performance Without Compromise
Best for: Databases, virtualization, mission-critical workloads
Minimum drives: 4
RAID 10 combines mirroring and striping. Drives are paired and mirrored, then data is striped across those pairs. This delivers both high performance and strong fault tolerance.
As long as failures occur in different mirrored pairs, the array stays online. For systems that need speed, consistency, and reliability all at once, RAID 10 is often the best choice.
- Fault tolerance: Multiple failures (depending on which drives fail)
- Performance: Excellent
- Usable capacity: About 50%
RAID at a Glance
| RAID Level | Protection | Performance | Usable Capacity | Common Uses |
| RAID 0 | None | Very High | High | Temporary, high-speed workloads |
| RAID 1 | High | Moderate | Low | Critical system data |
| RAID 5 | Moderate | Good | Good | File and application servers |
| RAID 6 | Very High | Moderate | Moderate | Large-capacity arrays |
| RAID 10 | Very High | Very High | Moderate | High-performance systems |
Hardware RAID, Software RAID, and NVMe RAID
RAID today isn’t just about traditional hard drives and SATA or SAS SSDs. With the rise of NVMe storage, a new class of RAID architectures has emerged—one designed specifically for ultra-high-speed, low-latency flash.
In modern rugged and high-performance systems, RAID typically falls into three categories:
Software RAID
Software RAID is handled by the operating system. It’s flexible and cost-effective, but it relies on the CPU for parity calculations and data management. That means performance can drop under heavy load, and recovery times may be longer—especially in systems with large drives or high I/O demands.
Hardware RAID (Controller-Based)
Traditional hardware RAID uses a dedicated controller card with its own processor and memory. These controllers manage parity, caching, and drive recovery independently of the system CPU. Features like battery-backed cache and advanced monitoring make hardware RAID a strong fit for rugged, mission-critical deployments where reliability and predictable performance matter.
This model works extremely well for SATA and SAS SSDs and HDDs, and it remains a core part of many Crystal Group storage solutions.
NVMe RAID (High-Performance Flash RAID)
NVMe drives operate at a completely different speed and bandwidth level than SATA or SAS. Because of that, conventional RAID controllers can become a bottleneck. To solve this, NVMe RAID systems use specialized architectures designed specifically for PCIe-based flash.
There are two primary ways NVMe RAID is implemented:
- GPU-Accelerated NVMe RAID
Solutions like GRAID use an NVIDIA GPU to handle parity and RAID processing in parallel, delivering extremely high throughput with very low latency. This approach is especially useful for workloads like video processing, AI pipelines, and real-time analytics. - ASIC-Based NVMe RAID
Other platforms, such as those built on Adaptec or Microchip controllers, use dedicated ASICs (Application-Specific Integrated Circuits) designed for NVMe RAID. These provide hardware-level acceleration without relying on a GPU, making them well suited for embedded, rugged, or power-constrained environments.
Both approaches allow NVMe drives to operate at full PCIe speeds while still providing RAID-level protection, something that software RAID alone cannot reliably deliver at scale.
For Crystal Group rugged systems, NVMe RAID is increasingly the preferred option when applications demand extreme bandwidth, low latency, and data protection—whether the system is deployed in a data center, at the edge, or in the field.
How to Choose the Right RAID Setup
There’s no one-size-fits-all answer. Start by asking a few practical questions:
- Need maximum speed? RAID 0 or RAID 10
- Focused on uptime and protection? RAID 6 or RAID 10
- Trying to balance capacity and reliability? RAID 5 or RAID 6
- Supporting a small but critical workload? RAID 1 or RAID 10
- Running NVMe-based storage with high throughput needs? NVMe RAID (GPU- or ASIC-based) to maintain performance without sacrificing data protection.
Also think about how the system will be used day to day. Read-heavy or write-heavy workloads, drive size, and rebuild times all matter—especially with modern high-capacity drives.
Final Thoughts
RAID is still one of the most effective tools for building resilient storage systems, particularly in rugged and mission-critical environments where failure isn’t an option. With the right RAID level and a solid hardware foundation, you can protect data, maintain performance, and keep systems running when it matters most.
If you’re unsure which RAID configuration fits your Crystal Group system or deployment, our storage experts are always happy to help you talk through the options.