QLC vs HDDs: The Battle for High-Capacity Storage

For enterprises, data storage is not just a technical challenge but a financial one. IDTechEx's new report, "Emerging Memory and Storage Technology 2025-2035: Markets, Trends, Forecasts", provides an in-depth analysis of the evolving storage landscape and its impact on cost, efficiency, and scalability. A 2022 Seagate study found that some organizations dedicate up to a third of their IT budget to storage, with 90% concerned about rising costs. With inflation, energy prices, and compute-heavy workloads further driving up cloud expenses, businesses are rethinking their approach to storage.

 

Historically, HDDs have dominated large-scale storage, offering low-cost, high-capacity solutions for cold and archival data. However, rising energy costs and the demand for better performance have positioned QLC (Quad-Level Cell) SSDs as a serious alternative, especially for read-intensive workloads. With superior power efficiency, storage density, and operational simplicity, QLC SSDs are increasingly challenging HDDs on Total Cost of Ownership (TCO).

 

This article examines the shifting role of HDDs, the rapid advancements in QLC SSD technology, and whether QLC SSDs are ready to challenge HDDs in cold storage and beyond, drawing insights from IDTechEx's in-depth market analysis.

 

 

For decades, HDDs were the backbone of digital storage; they were used across everything from consumer laptops to enterprise data centers. However, the landscape has shifted. As solid-state drives (SSDs) have become faster, have higher capacity, and are more affordable, HDDs have steadily retreated from high-performance and consumer markets. As of early 2025, SSDs are the standard in most edge devices and consumer electronics due to their speed, compact form factor, and durability.

 

This transition is reflected in both market structure and financial data. Where there were once over a dozen major HDD manufacturers, decades of mergers, acquisitions, and shutdowns have consolidated the industry to just three dominant players: Seagate, Western Digital, and Toshiba. As competition dwindled, innovation in the consumer space slowed, and vendors increasingly focused on high-capacity drives for data centers and enterprise markets.

 

 

The numbers back that strategic shift. In 2024, the HDD market generated US$15.1 billion in revenue, with Seagate and Western Digital each holding roughly 40% of the market and Toshiba covering the remaining market. However, most of this revenue is now concentrated in mass capacity drives, more specifically nearline HDDs, which are primarily used in data centers and enterprise storage systems. Seagate alone reported that 72% of its 2024 revenue came from mass capacity HDDs—up from 65% in 2023. Mass capacity HDDs accounted for 89% of the total exabytes shipped, with nearline HDDs contributing 78% of that total. Meanwhile, unit shipments continue to decline across the HDD industry, while average selling prices (ASPs) steadily increase, reflecting the growing share of high-cost, high-capacity drives in the product mix. Currently, nearline HDDs make up around 60% of total HDD revenue, but IDTechEx forecasts that figure will exceed 95% by 2035 as mass capacity drives become the sole stronghold for HDDs in the face of growing SSD adoption.

 

 

To keep pace with rising storage demands, HDD innovation has increasingly centred on boosting both capacity and performance, particularly for large-scale, cost-sensitive deployments. Modern drives have already crossed the 30TB threshold, with Western Digital's 32TB Ultrastar DC HC690 launched in 2024 and Seagate's 36TB Mozaik 3+ announced in early 2025. These milestones are part of a broader push toward more compact, energy-efficient, and higher-density storage, essential qualities as data centers face mounting pressure to reduce operational costs and environmental impact. This leap in capacity is being driven by advanced Energy-Assisted Magnetic Recording (EAMR) techniques, including Heat-Assisted Magnetic Recording (HAMR) and Microwave-Assisted Magnetic Recording (MAMR). These next-generation technologies overcome the physical limitations of conventional perpendicular magnetic recording (PMR) by enabling greater areal density. This not only increases raw capacity but also improves performance and scalability, allowing fewer drives to serve growing workloads more efficiently. Looking ahead, HDDs exceeding 50TB are expected as early as 2026-2027. However, as SSD technologies—particularly QLC NAND—continue to evolve, they are starting to challenge HDDs not only on performance, but increasingly on capacity and cost-effectiveness, raising the question of whether flash-based storage could encroach on HDD territory even in large-scale, cold storage environments.

 

 

While HDDs continue to dominate cold storage today, QLC NAND SSDs are emerging as a serious challenger. First introduced in 2018 by Intel and Micron, QLC SSDs store four bits per cell, enabling significantly greater storage density than earlier NAND types like TLC or MLC. This architectural shift allows for larger capacities at a lower cost per gigabyte—a critical factor in large-scale storage environments. One of QLC's defining advantages is its ability to scale to extreme capacities. Since its launch, capacity growth has accelerated, with Solidigm and Samsung releasing 61TB models in 2023. By late 2024, Solidigm introduced QLC SSDs exceeding 120TB, with Samsung and Western Digital expected to follow suit in 2025. To put that into perspective, this is over three times the capacity of the largest enterprise HDDs.

 

This leap in capacity is matched by performance, efficiency, and scalability. Solidigm's 122TB QLC SSD achieves sequential read speeds over 7 GB/s, compared to just 300 MB/s for HDDs, while latency is 20-100 microseconds versus ~4 milliseconds for enterprise HDDs. These performance gains accelerate AI, analytics, and real-time workloads, making QLC SSDs an increasingly compelling alternative for modern applications. Power efficiency is another key battleground. A Solidigm-Signal65 study found that QLC SSDs deliver up to 79.5% greater power efficiency than HDDs and enable 26.3% more AI infrastructure capacity within the same data center footprint. Comparing Solidigm's 122TB QLC SSD (D5-P5336) to Western Digital's 32TB Ultrastar DC HC690 HDD further illustrates this shift. The Solidigm drive achieves a power efficiency of 4.88 TB/W, outperforming the Ultrastar's 3.4 TB/W— a 43% improvement. This means QLC SSDs store significantly more data per watt consumed, a crucial advantage as data centers face rising energy costs and power constraints. Capacity density is another major advantage. The Solidigm QLC SSD reaches 17.4 GB/mm², compared to 2.14 GB/mm² for the Ultrastar HDD—an 8x increase. This higher density enables greater storage consolidation, reducing rack space and infrastructure costs—a key priority for hyperscale data centers. Additionally, Solidigm's QLC SSD is up to six times smaller in volume than its HDD counterpart, further enhancing scalability in space-constrained environments.

 

Beyond capacity and efficiency, QLC SSDs are also gaining traction due to their read-optimized characteristics, making them ideal for AI inference workloads, archival storage, backups, and large-object storage. As flash costs decline, QLC is narrowing the cost-per-terabyte gap with HDDs, coming closer to parity in total deployment cost, especially when factoring in performance, density, and operational simplicity. With growing capacities and efficiency gains, QLC SSDs are becoming an increasingly competitive alternative, offering improved cost per terabyte, capacity density, and capacity-to-power ratio, challenging HDDs even in traditionally HDD-dominated storage applications.

 

 

For those looking to understand the full picture, IDTechEx's new report, "Emerging Memory and Storage Technology 2025-2035: Markets, Trends, Forecasts", provides the most comprehensive assessment to date of the shifting memory and storage landscape. This includes:

 

Whether you are a storage vendor, hyperscaler, enterprise architect, or strategic decision-maker, this report delivers the critical insights needed to navigate the future of memory and storage. Discover where the industry is going—and what it means for your technology and business.

 

To find out more about this IDTechEx report, including downloadable sample pages, please visit www.IDTechEx.com/Memory.

 

For the full portfolio of semiconductors, computing, and AI market research available from IDTechEx, please see www.IDTechEx.com/Research/Semiconductors.

IDTechEx provides trusted independent research on emerging technologies and their markets. Since 1999, we have been helping our clients to understand new technologies, their supply chains, market requirements, opportunities and forecasts. For more information, contact research@IDTechEx.com or visit www.IDTechEx.com.