You’ve Just Crossed Over Into…The SMR Zone

Today, there’s a growing variety and volume of digital stuff. From images and videos shared on social sites, to high resolution medical and scientific scans, to machine-generated and sensor data, most of the data is created, stored and read infrequently, especially as it ages. In most cases it’s rarely modified. But if you could keep more of this stuff and make it readily accessible, its value increases. That’s both the challenge and the opportunity for data storage today.


Keeping Up With Stuff – The Areal Density Race

Our heritage traces back to the world’s first hard disk drive (HDD) invented in 1956 with a whopping 5MB of storage, and since then there’s been a technological arms race between companies to deliver HDDs with higher densities and better efficiencies.

In a HDD, data is written in “tracks”, concentric rings of magnetic regions separated by smaller rings or “gaps”. Looking like a sliced onion, tracks are always separated by a gap. HDDs have always used this layout.

With every generation of product, our researchers and engineers use their magic to shrink the “magnetic domain” required to store data. By “shrinking” the size of the bits, we can make tracks narrower and pack more of them into the same physical space, increasing areal density. Not sure if it sounds tough, but it is. It’s extremely tough.

More tracks also means more gaps— space not used to store data. What if we could reduce the number of those gaps? Could we use that newly freed real estate to store more data? Yes!

Cross Over Into The SMR Zone

In a conventional PMR (Perpendicular Magnetic Recording) HDD, applications have true random read/write capability because data is written in concentric tracks, separated by gaps. Any block in any track can be read, written or modified independently of others, making PMR HDDs ideal for data that is being updated regularly. We essentially trade capacity to gain accessibility and flexibility.



With SMR (Shingled Magnetic Recording) HDDs, we trade maximum accessibility and flexibility to gain capacity to store more stuff. We do this by writing the data sequentially, overlapping, or “shingling” each track of data, enabling more data tracks to be placed on each magnetic surface.


shingles2It’s like roofing a house. You start at the bottom and work your way up, carefully overlapping shingles in one direction, in an orderly fashion.

A SMR HDD still provides true random read capability—when you need a piece of data, you seek to it and read it like any other disk drive. But if you need to modify a piece of data, it’s a little different. Because the data you may want to modify is potentially “under another shingle” of data, you can’t directly modify it. You’ll have to move the row of shingles above it, and above that one, and so on.

Getting Zoned

It’s not efficient to move your data every time you want to modify or delete something, but there’s a couple of ways to help alleviate this problem.

First, we can group shingled tracks into “zones”, separated by a gap or “guard band” where data is not written. A SMR HDD can have virtually any number of zones, with trade-offs.

SMRzoneA SMR HDD with fewer, larger zones could achieve higher capacities because we’ve reduced the number of guard bands and used that space for additional shingled tracks of data. This option would be good for applications like long-term archiving, compliance records, or other “Cold Storage” data where the written data is “nearly-never” updated or deleted.

Another option is a SMR HDD with many more smaller zones. More zones means data can be more easily modified or deleted, but it also means we have more guard bands. The result is that we give up some capacity to enable flexibility. We’ve implemented this option in our recently announced 10TB HDD, as it supports broader use cases.

We can also be smarter about how to apply changes or deletes. Using sophisticated algorithms developed by our R&D team, we “collect” updates and deletes in a given zone to a reserved area, and when there’s enough of them, we apply them all at once. This helps improve overall performance.


That’s The Signpost Up Ahead— Your Next Stop, The SMR Zonecapacity growth

Although SMR technology may sound daunting with limits and caveats, it delivers a 25 percent increase in areal density, helping to store more stuff. It’s also the foundation for multiple generations of high capacity HDDs in the future with cost-effective $/TB.

Coupled with other innovations such as our HelioSealTM technology, we announced the world’s first enterprise-class 10TB HDD. SMR HDDs, including our 10TB product, are ideal for cool and cold storage applications where data is seldom, if ever, modified such as active archiving, social media and other applications where the highest density storage, low TCO and leading $/TB are critical factors.

Do you want to be left behind in the twilight zone of choosing what data is important, what data to store and what to discard? Or are you ready to cross over to the SMR zone?

(Please note: this post contains forward-looking statements. Please see our notice regarding forward looking statements.)