Is IronWolf a CMR or SMR?

Hard disk drives (HDDs) use either conventional magnetic recording (CMR) or shingled magnetic recording (SMR) technology. CMR drives have been around for decades and arrange tracks on the disk platters in parallel. This allows tracks to be individually written and updated without affecting adjacent tracks. SMR is a newer technology that overlaps tracks to pack more data onto each platter. However, only full rewrite of overlapping tracks is permitted, reducing performance in some scenarios.

What is CMR?

CMR stands for “Conventional Magnetic Recording” and refers to a traditional hard drive technology that stores data on tracks that do not overlap. With CMR drives, each track is separated from the next by a guard band, allowing data to be rewritten freely without affecting adjacent tracks (

CMR technology has been used in hard drives for decades and is considered the standard method of constructing hard drive disks. Some key features of CMR drives include:

  • Higher performance – CMR drives allow for random writes and rewrites without impacting adjacent tracks.
  • More reliable – The dedicated tracks prevent overwritten data issues that can occur with overlapping tracks.
  • Backward compatibility – CMR drives work with any host system and OS without compatibility issues.

Overall, CMR drives provide fast, reliable storage well-suited for a variety of applications from personal computing to enterprise data centers ( The conventional non-overlapping design is proven technology that offers predictable performance.

Benefits of CMR

CMR, or conventional magnetic recording, offers several key benefits compared to other storage technologies like SMR. Most notably, CMR provides better performance in terms of speed and reliability.

CMR hard drives can achieve faster sequential read/write speeds thanks to their simpler shingled magnetic recording design. This allows the drive heads to write to any track on the platter without needing to rewrite adjacent tracks, reducing write amplification. Tests show CMR drives provide sequential speeds up to 260MB/s for reads and writes (Source).

In addition, CMR drives offer lower latency and better random access performance. The drive head can quickly access any data on the platter without delays required by SMR drives. This provides snappier response times for accessing files scattered across the drive.

Finally, CMR drives are typically more reliable than SMR. By avoiding the complex shingled writing of SMR, CMR reduces the likelihood of data errors or failed writes. Studies show CMR drives have lower annualized failure rates around 0.8-1.2% compared to over 2% for SMR (Source). This improved reliability makes CMR well-suited for mission critical storage and frequently accessed data.

What is SMR?

SMR stands for Shingled Magnetic Recording. It is a storage technology used in some hard disk drives (HDDs) to increase storage density and overall drive capacity. With SMR, the data tracks on the disk are partially overlapped or “shingled” (like roof shingles) which allows more tracks to be written in the same area 1.

The key advantage of SMR is the ability to cram more data onto each disk platter. However, the overlapping tracks make writing data more complex. SMR drives must use algorithms to write sequentially and avoid overwriting adjacent tracks 2. This can negatively impact performance in certain workloads.

In summary, SMR is a technique to increase HDD capacity by overlapping the data tracks. But it comes with tradeoffs in performance and complexity.

Drawbacks of SMR

SMR drives have some significant drawbacks compared to CMR drives, primarily related to slower write speeds and decreased reliability. Since SMR drives overlap tracks, writing new data requires rewriting existing overlapping tracks first. This process is very slow compared to CMR drives which can write to empty tracks immediately (Source). The slower write speeds of SMR can cause problems like long save times, lagging applications, and reduced performance.

The overlapping track design also makes SMR drives less reliable than CMR. As tracks are rewritten, there is a higher likelihood of corrupted data. SMR drives have higher failure rates, especially when used in RAID setups or other heavy write environments. The technology relies on algorithms to manage the overlapping tracks and prevent data loss, but this is less robust than CMR’s independent tracks (Source). Overall, SMR’s architecture introduces vulnerabilities that impact performance and reliability.

Seagate IronWolf

The Seagate IronWolf series are high-performance internal hard disk drives designed specifically for network-attached storage (NAS) systems. IronWolf drives utilize NASware firmware for increased reliability, agility, and performance when used in RAID environments. According to Seagate, IronWolf drives are optimized for extreme workload rates of up to 180 TB/year and support up to 24 bays.

Key features of the IronWolf line include:

  • Available capacities from 1TB to 18TB
  • 7200 RPM spindle speeds (5900 RPM for larger capacities)
  • SATA 6Gb/s interface
  • 256MB cache buffer
  • Workload rating of 180 TB/year
  • 3 year limited warranty
  • RAID optimization via NASware firmware
  • Vibration protection and ramp load technology

Overall, the IronWolf series provides reliable, high-performance storage for NAS environments requiring 24/7 accessibility. The drives are tuned for multi-bay RAID configurations while still being cost-effective.

IronWolf CMR Confirmation

Based on several statements and specifications from Seagate, it is clear that IronWolf hard drives use CMR technology across the entire product range. Seagate states on their website listing all CMR and SMR drives ( that all IronWolf models from 1TB to 10TB+ are CMR drives. There is no mention of SMR for any capacities of IronWolf.

Reddit users on r/Seagate have also received confirmation from Seagate support that IronWolf drives are CMR ( One user even stated Seagate called them back to confirm the CMR technology after purchasing IronWolf drives.

Furthermore, IronWolf specifications match those of traditional CMR drives, with features like dual-plane balancing technology for consistent performance during multi-drive access. The performance and reliability of IronWolf would not be possible using SMR.

Benefits of IronWolf

IronWolf drives are designed specifically for NAS systems and optimized for performance, speed, and reliability. According to Seagate, IronWolf drives deliver incredible performance thanks to IronWolf Health | Seagate US. They utilize multi-user technology to handle demands from multiple users simultaneously and have a high workload rate limit of 180 TB/year for optimal endurance. The drives also have rotational vibration sensors to maintain consistent performance even in dense multi-drive systems.

In benchmarks, IronWolf drives achieve noticeably faster speeds compared to other NAS drives. For example, the IronWolf Pro 18TB drive reaches speeds up to 260MB/s, while competing NAS drives max out around 250MB/s Why We Use Seagate IronWolf Drives in Our NAS Solutions. This extra performance provides a snappier experience when accessing and transferring files.

Reliability is also a key highlight of IronWolf. The drives are rated for 1M hours MTBF and include a 5-year limited warranty. Advanced health monitoring tracks drive conditions to spot failures before they happen. Seagate even includes 3 years of free data recovery service with up to a 95% success rate, ensuring your data stays safe in case of unexpected issues.

IronWolf vs Competitors

When choosing a NAS hard drive, one of the key considerations is whether the drive uses CMR or SMR technology. Seagate’s IronWolf NAS drives utilize CMR, while some competing drives use SMR.

SMR (Shingled Magnetic Recording) allows drives to have higher storage density by overlapping tracks, but this can negatively impact performance, especially for NAS workloads involving multiple simultaneous read/write operations. SMR drives may experience slow write speeds and even temporary freezing when handling heavy workloads.

In comparison, IronWolf uses conventional CMR (Conventional Magnetic Recording) technology. The non-overlapping tracks provide consistent, reliable performance even under heavy workloads. This makes CMR better suited for the demands of NAS environments.

Major NAS drive competitors like Western Digital switched their Red NAS drives to SMR starting in 2019. However, Seagate has continued using CMR technology in the IronWolf lineup to optimize performance. This gives IronWolf a key advantage over competing SMR-based NAS hard drives.

For users looking to build or upgrade a high performance NAS, IronWolf’s CMR technology provides an excellent option over SMR drives. The consistent performance can better handle demanding workloads like Plex media servers, photo/video editing, virtualization, and more.



In summary, Seagate IronWolf NAS hard drives utilize conventional magnetic recording (CMR) technology rather than shingled magnetic recording (SMR). CMR is better suited for the demands of network-attached storage than SMR, providing faster write speeds, more reliability for frequently rewritten data, and better performance consistency overall.

For home and business users who need dependable, high-capacity internal drives for their NAS enclosures, IronWolf delivers on CMR benefits. Seagate designed the IronWolf line specifically for 24/7 operation under NAS workloads, leveraging CMR to enable seamless storage expansion and robust support for multi-user environments.

By relying on proven CMR technology rather than the compromises of SMR, Seagate’s IronWolf NAS hard drives stand apart from competing consumer-grade options. For those seeking optimized CMR performance to maximize their NAS experience, IronWolf represents an ideal solution.