MLC vs. TLC: Which Is the Better SSD?

Both multi-level cell (MLC) and triple-level cell (TLC) solid-state drives (SSDs) have played pivotal roles in the evolution of flash storage. However, the landscape has shifted dramatically in recent years, with TLC and even quad-level cell (QLC) technologies now dominating both consumer and enterprise markets. MLC SSDs, once the standard for high-performance applications, are increasingly rare, as manufacturers focus on higher-density, lower-cost NAND to meet massive data growth and sustainability goals.

In this article, we’ll review the key differences between MLC and TLC SSDs—including cost, performance, reliability, and endurance—and discuss how modern enterprise storage solutions like Pure Storage® FlashArray™ leverage advanced flash technologies to deliver optimal outcomes for today’s workloads.

MLC vs. TLC: What Are the Key Differences?

MLC SSDs store two bits of data per cell, while TLC SSDs store three. This means TLC NAND offers higher storage density, which translates to larger capacities and lower cost per gigabyte. However, the increased number of bits per cell also introduces greater complexity in voltage management, affecting endurance and performance.

How Voltage Levels Store Data

NAND flash memory stores data by trapping electrons in floating gate cells. Different voltage levels represent different bit patterns—when data is written, precise amounts of electrical charge are injected into each cell. During read operations, the storage controller measures the voltage level and translates it back to bits. MLC must distinguish between four voltage levels (for two bits), while TLC must differentiate between eight levels (for three bits). The controller must precisely measure these voltage levels to determine what data is stored—distinguishing between more levels takes additional time and complexity.

Understanding SSD Architecture

An SSD combines NAND flash memory with a controller and interface that enables the drive to function as a drop-in replacement for traditional hard-disk drives. SSDs include a flash translation layer (FTL), which is internal firmware designed to manage wear leveling, error correction, and bad block management while translating between logical and physical addresses.

It’s important to note that, as of 2025, TLC is now the mainstream technology for most SSDs, with QLC (four bits per cell) rapidly gaining traction for capacity-optimised workloads. MLC is now mostly found in legacy systems or niche applications requiring very high endurance.

Cost: TLC Drives the Economics

TLC SSDs are generally less expensive than MLC SSDs due to their higher storage density and lower cost per bit. This cost advantage has made TLC the default for most new deployments from laptops to data centers. The price gap between TLC and QLC is also narrowing, further accelerating the shift away from MLC.

Reliability and Endurance: Not Just a Numbers Game

Traditionally, MLC SSDs have offered higher reliability and endurance than TLC, as fewer voltage levels per cell reduce the risk of data errors and cell wear. However, advances in controller technology, error correction, and wear-leveling algorithms have significantly improved TLC endurance and reliability, making it suitable for demanding enterprise workloads. Modern TLC SSDs can now deliver endurance and data integrity that rival or surpass older MLC drives, especially when combined with advanced flash management software.

Performance: TLC Catches Up

MLC SSDs have historically outperformed TLC due to faster program/erase (P/E) cycles and simpler voltage management. Yet, with innovations like NVMe interfaces, multi-channel controllers, and intelligent caching, TLC SSDs now deliver performance that meets or exceeds the needs of most applications—including databases, virtualisation, and analytics. In fact, many enterprise all-flash arrays are built entirely on TLC or QLC NAND, leveraging software to optimise performance for diverse workloads.

Use Cases: Where Each Technology Fits Today

MLC SSDs are now primarily used in legacy systems, industrial environments, or specialty applications requiring extreme endurance (such as high-frequency trading or mission-critical logging).

TLC SSDs have become the standard for both consumer and enterprise storage, powering everything from personal devices to large-scale cloud and AI environments. With the rise of QLC, TLC is increasingly used for performance-sensitive workloads, while QLC is chosen for capacity-oriented, read-intensive applications such as backup, content repositories, and data lakes.

Direct to NAND: The Unique Advantage of Pure Storage

The Pure Storage Purity operating system is unique in the industry—it's the only storage operating system that bypasses the SSD entirely and directly accesses the NAND through DirectFlash® Modules. This eliminates the FTL, which is an extra component that can fail, consumes electricity, and adds unnecessary latency. By removing this layer, Pure Storage arrays provide proper wear leveling across all NAND in the array, delivering better performance and endurance regardless of whether using MLC, TLC, or QLC NAND.

The Pure Storage Approach: Beyond MLC and TLC

Pure Storage has moved beyond the limitations of commodity MLC and TLC SSDs by engineering its own DirectFlash Modules (DFMs), which communicate directly with raw NAND for maximum efficiency and longevity. This approach enables Pure Storage to deliver higher density, lower latency, and better cost efficiency than traditional SSD-based arrays. As of 2025, Pure Storage ships DFMs up to 150TB (and soon 300TB), far surpassing the capacity and efficiency of off-the-shelf SSDs. 

Pure Storage FlashArray//C™, a capacity-optimised all-flash array, now leverages enterprise-grade QLC NAND, offering 99.9999% availability, non-disruptive upgrades, and consistent single-millisecond latency for business-critical workloads. This platform is ideal for organisations consolidating workloads, deploying hybrid cloud strategies, or seeking to replace legacy hybrid and HDD-based systems with a sustainable, future-proof solution. 

Key Benefits of Modern All-flash Storage with Pure Storage

• Radically improved density and energy efficiency, reducing data centre footprint and power consumption by up to 85% compared to legacy arrays
• Consistent, predictable performance for both performance-sensitive and capacity-oriented workloads
• Evergreen architecture for non-disruptive upgrades and zero planned downtime
• Unified management across block, file, and object storage with Pure Fusion™
• Enterprise-grade reliability and data protection, including advanced cyber resilience

Conclusion

The question of MLC versus TLC is less relevant for modern storage buyers, as TLC (and now QLC) has become the standard for most new deployments. Thanks to advances in flash management, controller technology, and software innovation, TLC-based solutions can now deliver the performance, endurance, and reliability required by today’s most demanding workloads—at a fraction of the cost and environmental impact of older technologies. Pure Storage DirectFlash Modules and FlashArray platforms exemplify this evolution, providing unmatched efficiency, simplicity, and resilience for the data-driven enterprise.