SMR HDD Technology – What’s It And What Can It Do

SMR HDD technology 1 We use hard disk drive (HDD) almost every day and it’s an indispensable part of computer. However, it’s a pity that most of the computer users don’t know much about this kind of drive. How it works? What’s the storage principle of data in hard drive? What are the technologies that have been adopted in hard disk drive?

Many questions like this are unfamiliar to users. Taking this into consideration, we’d like to talk about the traditional and mainstream recording method – Perpendicular Magnetic Recording (PMR) at first. Then, introduce the newly appeared hard drive recording method – Shingled Magnetic Recording (SMR) – and the way to recover data from archive HDD. In short, we focus on SMR HDD technology and SMR data recovery.

Magnetic Recording Technology

As you can notice, we have already stepped into the information age, in which data experience an explosive growth and the requirement for storage technology keeps increasing. The growing demand for high storage capacity, fast data access speed and high cost effective storage device worked together to further promote the development of storage recording technology.

As a result, the performance of traditional storage recording technology is getting higher and new storage recording technology keeps emerging, so that information storage has become one of the most active IT fields currently.

Appeared in 1898, magnetic recording technology has crossed a whole century and become a traditional & mainstream storage recoding technology. Now, magnetic recording devices have been applied widely in both consumer electronics and professional applications fields. The fact is that the rise of optical recording technology and the development of solid storage technology destroyed the domination position of magnetic recording technology.

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However, magnetic recording technology still glow with exuberant vitality so far thanks to its continuous breakthrough in recording medium, read and write head, digital channel and other technical aspect. With the continuous improvement of performance, the application of magnetic recording technology is getting wider. Among today’s various information storage technologies, magnetic recording technology is still the most important one.

Now, all the countries in the world, especially those developed countries attach great importance to the development of magnetic recording technology, so the related research and development work is very active. Various magnetic related professional conferences have been held regularly or irregularly throughout the world, including MRM, PMRC, NAPMRC, INTERMAG and MMM. Now, let’s introduce two magnetic recording technologies to you: PMR and SMR


Over the past few decades, the magnetic recording technology and recording density have been developing rapidly under the hard work of numerous scientists. Traditional magnetic recording modes mainly include: LMR (Longitudinal Magnetic Recording), PMR (Perpendicular Magnetic Recording), TMR (Tilted Magnetic Recording) and HAMR (Heat-assisted Magnetic Recording). Among those recording modes, PMR is widely used in hard drive, so we decide to lay emphasis on it.

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In order to solve the difficulty that LMR encounters during high-density recording, Iwasaki professor, from Tohoku University, proposed the concept of perpendicular magnetic recording in 1977. In PMR mode, the magnetization direction of storage medium is perpendicular to the disk platter. After comparing LMR with PMR, we found: because of the static magnetic interaction, LMR is stable at low recording density while PMR is stable at high recording density during recording. This essential difference between them implies the change of magnetic recording mode from LMR to PMR is inevitable.

PMR has many requirements for the recording medium. Here, we list some of them:
  • It should be provided with a relatively high uniaxial magnetic anisotropy perpendicular to the medium surface. The easy-to-magnetize axis of grain medium (continuous film) or particle (powder-coated medium), which is used to form storage medium, should be parallel to each other as much as possible.

  • Saturation magnetization and the residual magnetization perpendicular to the plane of the medium should be suitably high, so as to improve the SNR (Signal to Noise Ratio) of reproduction voltage.

  • Magnetization curve should be a rectangular in the vertical direction, but it should be a straight line in the medium surface.

  • Coercive force should be relatively high in order to raise output voltage, SNR (Signal to Noise Ratio) and record resolution.

  • Other features: good uniformity, chemical stability, thermal stability, abrasion resistance and flexibility, cheap raw materials, easy mass production and low cost.

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SMR, which stands for Shingled Magnetic Recording is a newly designed HDD recording technology; it has been developed to increase density, or we can say, break the limit of traditional PMR (Perpendicular Magnetic Recording).

The architecture of SMR creates a new set of challenges, which have effect on both performance and compatibility. Besides, it is said that SMR technology will be applied widely in archive, data backup and repository in the near future. Environments like WORM (Write Once Read Many) and object storage are suitable for SMR, benefiting from its performance characteristics. For organizations and other institutions which have massive amounts of data and which require a value-centric alternative to the current near line offerings, SMR seems to be a perfect choice.

However, there’re other voices that considering SMR as a totally stopgap measure in many ways. They think it's necessary and worthwhile to wait for the arrival of more advanced recording techniques, such as HAMR and BPM. Yet, they can’t deny the fact that SMR is going to be used for many years because of its compatibility with emerging recording techniques and more importantly, its low cost. It is just because of this that we think it’s essential to choose SMR technology as our topic to show more details of SMR to the public.

Till now, the SMR HDDs providing by different vendors are penetrating into enterprises and home users. The SMR HDD is compatible with storage and server OEMs. At the very beginning, SMR HDD is too expensive to afford for many users since SMR HDD technology is rare, but now, the price has been pushed down to as low as 3 cents per useable GB.

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What about the Reliability of SMR

Though knowing that SMR HDD has been used by lots of home users and agencies, some users still want to know the shingled magnetic recording reliability. They’ll decide to use HDD developed with this new kind of technology only after figuring out the practicability and reliability of SMR. So now, we decide to talk about this.

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Is SMR HDD really reliable? Perhaps different people have different answers on this point. But either Seagate or HGST (Hitachi Global Storage Technologies, which is a Western Digital’s wholly owned subsidiary that sells hard disk drives, solid-state drives, external storage products and corresponding services) haven’t given up the old and proven PMR (Perpendicular Magnetic Recording) technology. They both have their own 6TB PMR hard disk, which has an over 220MB/s read and write speed.

In some sense, PMR has reached its limit during the past few decades’ development. And the most reliable method to upgrade “disk storage density” is to change the way data are written into the hard disk. This mainly explains the origin of SMR (Shingled Magnetic Recording).

As a new generation of storage technology, shingled magnetic recording technology has indeed made a qualitative change in medium structure. It resizes the data storage way to further increase the track density and storage density per unit area by overlapping the track – just like the stacked roof tiles. The Seagate 8TB hard drive which uses this new technology has reached a single disc capacity of over 1.25TB. However, the read and write speed of it is only between 150 ~ 190 MB/s.

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To sum up, SMR technology helps to increase the storage density and capacity of hard drive at the expense of overall hard drive performance. So, this new kind of technology is not good enough; it does not compensate for the performance defects of mechanical hard disk (when it is compared to SSD). It is more like a transition technology that hard disk manufacturers rush to use to improve the situation currently, not to solve the problem fundamentally. Therefore, in our point of view, 8TB or even 10TB hard drive may be hardly to become a savior due to the limitation in output and production cost.

SMR in Seagate 8TB Archive HDD

In order to fully satisfy users’ increasing needs for more storage capacity, HDD vendors decide to adopt new technology with clever engineering to try their best to increase the amount of storage they can provide per device, as well as per dollar. The newest innovation which comes in the form of SMR rings the bell. It increases the amount of available storage capacity by just overlaying data tracks.

As far as we know, the Seagate 8TB archive HDD (also called Seagate 8TB SMR hard drive) adopts shingled magnetic recording technology and air filling technology; among those two technologies, the former is the bright spot. Since the realization of shingled magnetic recording technology is relatively difficult and the read and write stability and reliability are not easy to control, it has not been widely used till now.

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According to the test results, the read and write speed of Seagate 8TB archive HDD is not surprising; in addition to capacity, it has nothing special. HGST still uses the mature perpendicular magnetic recording technology, though helium filling technology cannot fully play its read and write speed advantage. The disc body of helium filling hard drive is the most important part, and it could carry SMR technology in the future. Thus, the hard drive capacity could be further enlarged.

As the first manufacturer to apply new head and disk drive technology, Seagate has overcome many obstacles of SMR technology and this is so ahead of other hard disk manufacturers. However, we find, just like we mentioned before, the whole shingled magnetic recording performance is not as good as we imagine. This can’t be attributed to the shortage of Seagate technology; instead, the limitation in current SMR technology is the main reason that should be responsible for the unpopularity of SMR HDD.

SMR Data Recovery – Can It Be Done or Not

SMR HDD technology is not as perfect as we expected and fails to solve some problems, but it still has its own market. Some users prefer to choose SMR HDD rather than traditional HDD, which uses PMR technology, to store their personal & business data. However, due to the limitation of SMR technology, data loss accidents may happen on SMR HDD more easily than on ordinary HDD. And if you’re careful enough, you’ll find a few users are encountering data loss on SMR HDD and don’t know how to achieve SMR data recovery.

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We feel it’s necessary to tell users that though there’re many differences between SMR HDD and ordinary HDD, their data storage principle is similar to each other. Thus, data loss tends to take place in both types of HDDs. Besides, their data recovery method is also similar to each other. As long as you find the suitable data recovery software which gives full support to SMR HDD technology, you can recover all your data missing accidentally from disk without any trouble.

Recover Data from Archive HDD Right Now

We provide a useful way here, hoping to help all users who’re suffering from logical data loss on SMR HDD/Archive HDD regain their lost data. Following 4 steps are needed to recover data from archive HDD.

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Step 1: confirm the cause of your HDD data loss, and then open MiniTool Power Data Recovery to select a functional module which is suitable for your data loss case. Just click on the module to start recovery.

Note: if you’re not sure about the reason why data are missing, please select “Damaged Partition Recovery” to recover when partitions are not lost or select “Lost Partition Recovery” to perform recovery when one or more partitions disappear mysteriously.

Step 2: select the drive which adopts SMR HDD technology and encounters accidental data loss and then press “Open”, “Scan” or “Full Scan” button to search for the lost data.

Step 3: look through the found data which are listed in software at the end of scan, and then check the ones you need to press “Save” to recover them out.

Step 4: go to see and check the recovered data to find out whether they’re all you want to recover. If the answer is positive, you could close the recovery software to end. If the answer is negative, instead, you should further use this software to accomplish complete recovery of missing data.

You can also make use of the “Settings”, “Find” or “Filter” function to narrow the searching range in order to discover needed data more directly.

Common problems related to partition recovery and our solutions: