Solid state drives (SSDs) are a popular storage technology that offer significant advantages over traditional hard disk drives (HDDs). SSDs have no moving parts, are silent, and have much faster read/write speeds. This makes them an attractive option for building fast and reliable storage solutions. One question that often arises is whether SSDs can be configured in a redundant array of independent disks (RAID) for improved performance and fault tolerance. The short answer is yes, SSDs can absolutely be used in RAID configurations.
Benefits of using SSDs in RAID
There are several key benefits to using SSDs in a RAID array compared to HDDs:
- Faster read/write speeds – SSDs are much faster than HDDs, so building a RAID array with SSDs can provide dramatic improvements to input/output operations per second (IOPS). This is ideal for applications that demand high throughput like video editing, 3D rendering, financial analysis and scientific computing.
- Lower latency – The fast access times of SSDs can greatly reduce latency when deployed in a RAID configuration. This leads to a more responsive system.
- Increased reliability – RAID provides increased data reliability through redundancy. Combining this with the resilience of SSDs that have no moving parts can result in a storage solution with very high availability.
- Better shock/vibration tolerance – Since SSDs have no platter or head that can crash or malfunction when moved, they can better withstand environmental vibration and shocks when used in RAID implementations for mobile or embedded systems.
- Smaller footprint – Multiple SSDs can provide terabytes of redundant storage capacity while taking up minimal space in a server or computing device. HDD RAID arrays are much larger and bulkier in comparison.
The synergies between SSDs and RAID technologies allow IT professionals to design storage infrastructures with previously unachievable metrics related to speed, consistency, durability and physical space requirements. For applications where performance, capacity and resiliency are critical requirements, SSD RAID arrays are an increasingly compelling solution.
Types of RAID that work with SSDs
SSDs are compatible with most of the most common RAID levels, including:
- RAID 0 – Also known as disk striping, RAID 0 spreads data evenly across all the disks in the array. It provides improved performance but no redundancy. SSD RAID 0 arrays deliver incredible speeds for applications like video production and scientific computing.
- RAID 1 – Also known as disk mirroring, RAID 1 duplicates all data on a secondary drive to provide fault tolerance. SSD RAID 1 arrays can provide consistent performance and protection against drive failure.
- RAID 5 – Uses distributed parity and striping to provide both speed and redundancy. SSD RAID 5 offers fast read/write combined with the ability to withstand a single drive failure.
- RAID 6 – Like RAID 5, but can endure up to two disk failures. The redundancy of SSD RAID 6 results in slightly slower write performance but maximum protection.
- RAID 10 – Configured as a striped set of mirrored drives, RAID 10 balances speed and redundancy for critical applications. SSD RAID 10 arrays are popular for transactional databases and application servers.
The most appropriate RAID level depends on the required balance between performance, capacity efficiency, and fault tolerance. With their versatility and performance advantages, SSDs are a smart choice for deploying both simple and complex RAID sets.
SSD-specific RAID considerations
While SSD RAID provides many benefits, there are some additional considerations when implementing RAID with flash-based SSDs versus traditional HDDs:
- Use enterprise SSDs for RAID – Consumer SSDs often have limitations around sustained write performance that make them less suitable for RAID environments. Enterprise SSDs are a better choice for RAID implementations. They use advanced controllers and firmware optimized for 24/7 operation under constant heavy workloads.
- Enable TRIM – The TRIM command improves sustained write performance and longevity of SSDs by proactively wiping deleted blocks. TRIM should be enabled for SSDs configured in RAID.
- RAID controller compatibility – Use RAID controllers certified and optimized for SSDs. Software RAID through operating systems works, but dedicated hardware RAID controllers reduce CPU load.
- Alignment and erase block sizes – Properly aligning SSD partition and filesystem boundaries to erase block sizes is important to optimizing performance. The RAID controller and disk utilities should handle this automatically.
- Drive lifespan – RAID extends the useful lifespan of SSDs by writing evenly across all disks. However, SSDs have a finite number of drive writes before wear-out. Adding spare drives and expanding capacity over time is recommended.
- RAID rebuild times – Rebuilding an SSD RAID set goes faster than HDD RAID given the faster write speeds of SSDs. This minimizes vulnerability to additional disk failures during rebuild.
Proactively addressing these factors helps ensure optimal performance and longevity when architecting SSD-based RAID storage.
Comparison versus HDD RAID
It is also informative to compare RAID arrays built with SSDs versus traditional HDDs. Here is a head-to-head look at the key differences:
| SSD RAID | HDD RAID | |
|---|---|---|
| Read speed | Much faster | Slower |
| Write speed | Much faster | Slower |
| Latency | Ultra-low | Higher |
| Capacity efficiency | Lower (improving with larger SSDs) | Higher |
| Physical size | Much smaller | Bulky, consumes more space |
| Noise | Silent | Audible disk activity |
| Power efficiency | More efficient | Less efficient |
| Shock/vibration tolerance | Much higher | Sensitive, may fail |
The faster speed, lower latency, and greater resilience clearly highlight the advantages of SSD RAID compared to legacy HDD RAID. The sole advantage of HDD RAID arrays remains higher capacity for lower cost. But as SSD costs continue to decline, SSD RAID has become the preferred solution any time performance and reliability are priorities.
When to choose SSD RAID
Given their advantages, SSD RAID arrays are best suited for applications that require:
- High throughput for heavy workloads (e.g. video production, analytics, simulations, high volume OLTP databases)
- Ultra-low latency response times (e.g. high frequency trading, industrial automation, augmented reality)
- Maximizing density in space-constrained deployments (e.g. hyperscale data centers, edge computing)
- Mission-critical data with little tolerance for downtime (e.g. utility operations, emergency services, life-or-death systems)
- Extreme physical shock/vibration resistance (e.g. defense, aerospace, industrial, transportation)
For more moderately demanding applications where performance needs are lower, HDD RAID can still offer a cost-effective solution. But for applications requiring the best combination of speed, reliability and resilience, SSD RAID has become the standard choice.
Notable vendors and products
Many leading vendors offer enterprise SSDs suitable for RAID deployments. Some examples include:
- Intel DC P3600/P3700 Series SSDs
- Samsung PM1633a SSD
- Micron 5100 MAX SSDs
- Seagate Nytro Series SSDs
- Western Digital Ultrastar SN200 SSDs
These vendors also provide RAID controllers specifically optimized for flash-based SSDs, like the Dell PERC H740P and Intel RAID RS3 controllers. Overall, SSDs from top-tier suppliers paired with compatible RAID controllers provide proven, reliable performance in RAID applications.
Conclusion
SSDs can absolutely be combined into high performance, resilient RAID arrays to meet demanding storage needs. Their high speeds, low latency, silent operation, and physical shock tolerance represent major advantages over traditional HDD RAID.
Utilizing enterprise-class SSDs and proper RAID controller alignment ensures optimal RAID performance with SSDs. For applications needing uncompromising throughput, response times, redundancy, and durability, SSD RAID has become the go-to solution for IT architects and system designers alike.
Thanks to steadily declining costs and rising densities, SSD RAID continues firmly on the trajectory to dominate the future of enterprise storage architectures for years to come.
