Is SMR good for HDD?

Shingled magnetic recording (SMR) is a magnetic storage data recording technology used in hard disk drives (HDDs) to increase storage density and overall storage capacity. SMR overlaps tracks on a platter like shingles on a roof to achieve higher storage density compared to conventional magnetic recording (CMR). HDDs record data on quickly rotating platters coated with magnetic material. Read/write heads floating on a cushion of air record and read data from the platters. SMR squeezes tracks closer together to fit more data on each platter, enabling higher capacities in the same physical space as CMR drives. However, SMR can impact performance in certain workloads.

According to Wikipedia, “Shingled magnetic recording (SMR) is a magnetic storage data recording technology used in hard disk drives (HDDs) to increase storage density and overall storage capacity.” SMR increases areal density by overlapping tracks in a shingle-like fashion.

History of SMR

The concept of small modular reactors (SMRs) dates back to the 1940s and 1950s when the U.S. military developed small reactors for use at remote sites like the McMurdo Station in Antarctica, according to The Forgotten History of Small Nuclear Reactors. The idea was that smaller reactors would be easier to construct, more affordable, and easier to transport than traditional larger reactors.

By the 1960s, early SMR designs were being developed by companies like Westinghouse and GE, according to the Wikipedia article on SMRs. However, many of these early designs were shelved as the nuclear industry consolidated and focused on larger reactors to achieve economies of scale.

In the 2000s, interest in SMRs was revived as companies looked for ways to reduce the high capital costs associated with large nuclear plants. New modular construction techniques and simplified, standardized designs made SMRs more feasible and affordable. According to Small nuclear power reactors, over 50 different SMR designs are now being developed around the world.

Benefits of SMR

One of the key benefits of SMRs is increased storage density. By using shingled magnetic recording (SMR), hard disk drives (HDDs) can increase the amount of data that can be stored per platter. SMR overlaps tracks like shingles on a roof, allowing for higher track density. This enables SMR HDDs to offer larger overall storage capacities compared to conventional perpendicular magnetic recording (PMR) HDDs (, 2022).

In addition to increased density, SMR can result in lower costs for HDDs. By packing more data onto each platter, SMR HDDs require fewer platters and heads to reach a given capacity. This reduces the raw materials and mechanical components needed, lowering manufacturing costs. Overall, SMR HDDs provide more capacity per dollar compared to equivalent PMR HDDs. However, the increased density comes with some tradeoffs in performance (, 2022).

Drawbacks of SMR

SMRs do have some drawbacks that need to be considered. One is that their small size leads to certain performance limitations compared to traditional large nuclear reactors. According to the International Atomic Energy Agency (IAEA), “economies of scale make large reactors (1 GWe or higher) more financially attractive than SMRs.”

Large reactors can produce more power from fewer units and spread out operating costs. An SMR may generate enough electricity to power a small city, while a typical nuclear plant outputs enough for millions of homes. So in some cases, the efficiency and cost-effectiveness of SMRs may not match up to conventional plants [1].

Another drawback is potential compatibility issues. Since SMRs are a newer, less widespread technology, they may not fit as seamlessly into existing energy grids and infrastructure tailored for traditional large reactors. More investment and modifications to power transmission and distribution systems may be needed to integrate SMRs [2].

SMR Usage Cases

One of the main usage cases for SMR drives is archival and cold data storage. SMR allows for greater storage density and lower cost per terabyte, making it well-suited for data that is written sequentially and infrequently accessed, like archives, backups, media libraries, and other cold storage use cases. The sequential write performance of SMR works well for these large, sequential writes of data that will have few updates once written.

According to Seagate, SMR hard drives can offer over 20% more capacity than conventional drives, while still fitting standard 3.5-inch hard drive form factors (Seagate 2016). This increased density comes from more tracks being packed closer together. So for the same physical storage space, SMR offers substantially more capacity.

Backblaze, an online backup company, found SMR drives to have comparable failure rates to conventional HDDs in their data center deployments. They have increasingly adopted SMR drives for their backup storage pods due to the favorable economics. However, they caution that SMR is not appropriate for all workloads, and performance tradeoffs need to be considered (Backblaze 2020).

Overall, SMR’s strengths in density and sequential write make it well-matched to large, cold datasets like archives and backups that need cost-efficient bulk storage. But SMR is less appropriate for transactional, low-latency workloads.

Alternatives to SMR

While SMR HDDs provide higher storage density, other HDD technologies offer some advantages and may be preferable in certain use cases. Some key alternatives to SMR drives include:


Conventional magnetic recording (CMR) is the traditional HDD technology that was used before SMR. CMR writes tracks separately without overlapping, avoiding the performance drawbacks of SMR. However, CMR drives have lower maximum capacities compared to SMR. According to forums like Reddit’s r/DataHoarder, many users prefer CMR drives for applications requiring consistent performance like RAID arrays.


Newer technologies like microwave assisted magnetic recording (MAMR) and heat-assisted magnetic recording (HAMR) allow for increased densities similar to SMR, while avoiding the performance limitations of shingled writes. These technologies are still in development and not widely available yet. MAMR and HAMR drives may offer a good combination of high capacity and performance when they come to market.


For applications requiring the highest performance, solid state drives (SSDs) are the leading option. SSDs with NAND flash memory provide much faster reads and writes compared to any HDD technology. However, SSDs remain more expensive than HDDs for the same capacity. As SSD prices continue to decrease, they are displacing HDDs in more use cases.

SMR in the Data Center

The data center industry is exploring the use of small modular reactors (SMRs) to power facilities, which could provide benefits like reducing carbon emissions and lowering electricity costs (Source). However, utilizing nuclear power also comes with challenges.

A major hurdle is the regulatory requirements around nuclear energy, which can significantly slow down deployment. Data center operators interested in SMRs need to work closely with local and national agencies to navigate regulations (Source). There are also public concerns around safety that must be addressed through education and transparency.

From a technology standpoint, SMR designs are still evolving so there is uncertainty around optimal configurations. Factors like reactor size, cost efficiencies, and integration with renewable energy sources are still being optimized. Data centers piloting SMRs will need to be flexible as the technology matures.

Best practices for utilizing SMRs include starting with a small pilot installation, partnering with experienced nuclear energy companies, having robust physical and cyber security measures, and developing comprehensive emergency response plans. Careful planning and learning from initial implementations will help make the technology more viable over time.

SMR for Consumers

Shingled magnetic recording (SMR) hard disk drives (HDDs) are increasingly being used in consumer devices and desktop computers. The key benefits of SMR for home users are:

  • Lower cost per terabyte compared to conventional magnetic recording (CMR) drives
  • High storage densities, allowing for larger drive capacities
  • Moderate read/write performance suitable for typical home usage

However, SMR does have some downsides to be aware of:

  • Slower write speeds compared to CMR, especially for random writes
  • Not ideal for frequently overwritten data or applications with heavy write workloads
  • More complex data management required by the drive firmware

For general home office and entertainment usage like documents, photos, music, and media playback, SMR HDDs offer a cost-effective storage solution. But users looking to install programs/games or run virtual machines may want to consider CMR alternatives for better write performance. Overall SMR drives are a reasonable option for consumers focused on maximizing storage capacity.

According to reviews on reddit (, SMR HDDs work well for media storage and backup purposes in a home setting. But frequent rewriting of data can lead to slower performance over time. For non-intensive consumer usage, SMR provides good value. But high write-intensity applications are better suited to CMR drives despite their higher cost per TB.

The Future of SMR

The future of small modular reactors looks promising as the technology continues to advance and interest in SMRs grows globally. Some emerging implementations and improvements include:

Several companies like NuScale Power, Rolls-Royce, and Terrestrial Energy are developing and testing new SMR designs that are smaller, simpler, and cheaper to build than traditional large reactors. These aim to make SMRs more cost effective and deployable.

New manufacturing and construction techniques like using factory fabrication and modular construction can reduce costs and build times compared to on-site construction for larger reactors. This makes SMRs more affordable.

Some SMRs are being designed as micro-reactors that can provide under 50MW of power, ideal for remote communities or industrial applications like mining. These very small SMRs could expand how nuclear power is used.

Advanced SMR designs incorporate passive safety features that don’t require human intervention or backup power during emergency shutdowns. This improves safety and regulatory approvals.

High-temperature gas-cooled SMRs are being developed to not only generate electricity but also provide process heat for industrial purposes like hydrogen production. This increases the applications for SMRs.

Continued research aims to improve SMR technology even further in terms of costs, safety, size, modularity, and efficiency to make SMRs a viable source of clean, reliable, and affordable energy.


In summary, SMR technology offers both benefits and drawbacks compared to conventional hard disk drives. The main benefits of SMR are lower cost per terabyte of storage, higher storage density, and lower power consumption. However, SMR can suffer from performance drawbacks, especially when writing data. SMR drives need to pause and rearrange shingled tracks, which adds latency.

For most consumer uses, SMR provides a cost-effective way to add large amounts of storage. The performance limitations are unlikely to be noticed in typical consumer workflows like media storage and backup. However, SMR is not recommended for more demanding applications like server storage or as primary system drives.

Looking forward, SMR technology will likely continue improving to increase performance. Advanced caching algorithms help mask some of the inherent latency issues in SMR. Overall, SMR HDDs occupy an important market segment between high-capacity HDDs and more expensive SSDs for cost-effective bulk storage.