The Future of storage, or is the disk drive dead?

We are running out of places to put things.

Data continues to grow at a frightening rate. According to an IDC study there was about 281 Exabytes of data stored on disk in 2007 word wide. This data is growing at CAGR of about 70%. At this rate, in 3 years there will be about 1400 Exabytes of data sitting on disk.

Now, a lot of this data is sitting on people’s desktops, laptops, ipods, phones, digital cameras, etc. right now. However, things like cloud storage will change all of that. Heck, we are seeing some of the change right now with things like social networking sites, photo sharing sites, etc. IDC says that for 85% of that data a corporate entity will be responsible for the protection and security of the data.

So, in the future, we are going to have to store a lot more data than we do today, a LOT more data. How are we going to do that? Just the physical aspect of getting exabytes of data on the floor is going to be a challenge. I don’t even want to talk about protecting and managing that much data. But for now, I want to talk about the density of the hard disk drive since that’s going to soon become the physical limit of what we can store on the floor of our data centers.

The bits are getting too small!

Enterprise disk drive capacity has obeyed Moore’s Law and doubled every 18 months for quite a few years. However, this growth has appears to be slowing down over the last 5 years, and it is now taking approximately 29-30 months to double the capacity of an Enterprise disk Drive.

This shows that we are nearing the maximum areal density (max capacity) of current disk drive technology called the superparamagnetic limit. Areal density as it refers to disk drives is measured by the number of bits per inch (bpi) times the number of tracks per inch (tpi).

The areal density of disk storage devices has increased dramatically since IBM introduced the RAMAC in 1956. RAMAC had an areal density of two thousand bits per square inch, while current-day disks have reached 100 billion bits (100 gigabits per square inch). Perpendicular recording is expected to increase storage capacity even more over time, but we do appear to be approaching the limit.

As the magnetic bits get smaller, at some point they no longer hold their charge. Thermal fluctuations reduce the signal strength and render the bits unstable. However, this ultimate areal density keeps changing as researchers find new techniques for recording and sensing the bit. Years ago the limit was thought to be 20 gigabits per square inch. Today, the limit is several hundred gigabits per square inch, and more than a terabit is expected soon. But that’s about all you can get out of the technology.

Denser is faster.

Increasing the density of hard disk drives has a side benefit. It makes the drives faster as well. This is really quite logical when you think about it. Since the closer things are together on the drive, the more data passes by a read/write head in the same period of time thus making the drive faster.

Shorter term solution.

So, if the disk drive is not going to be able to continue to provide us with the kinds of capacities we are going to need in the future, what will? Well, there are a number of things that are being looked at by a lot of folks who are a lot smarter than me! But in the short term, things like SSD look promising once we work out some of the kinks. Specifically, the write speed issue. Until we can get that up I’m not sure how much general acceptance SSD technology is going to get. Price, I am convinced, will take care of itself as the scales of economy kick in. Holographic storage, some people have been working on this for a very long time and it seems like such a promising technology, but it has yet to come to fruition. There is one company out there that’s trying to ship a product, but they recently pushed off their release date until the end of this year. Still, if they can work out the kinks, it definitely has promise, especially for media applications. But what about beyond that? What technologies are the researchers looking at that sound really cool? I look at some of those next.

Sci-Fi data storage.

So, this is where it gets fun. Some of the technologies that researches are currently looking into really do sound like something out of a Sci-Fi movie. Here are some examples of the stuff I’m talking about:

Nanodots – A nanodot has north and south poles like a tiny bar magnet and switches back and forth (or between 0 and 1) in response to a strong magnetic field. Generally, the smaller the dot, the stronger the field required to induce the switch. Until now researchers have been unable to understand and control a wide variation in nanodot switching response. A NIST team significantly reduced the variation to less than 5 percent of the average switching field and also identified what is believed to be the key cause of variability. Nanodots, as small as 50 nanometers (nm) wide could be used to storage data.

Array’s of magnetic snakes – According to a weekly digest from the American Physical Society (APS), physicists at Argonne National Laboratory (ANL) have found that under certain conditions, magnetic particles could form magnetic ‘snakes’ able to control fluids. According to the researchers, this magnetic self-assembly phenomena may be used to make the next generation of magnetic recording media or transparent conductors based on self-assembled conducting networks of magnetic micro-particles.

Nanowires – Switchable fluorescent proteins, able to move reversibly between two optical states, have been known from some years. But now, German researchers have discovered the mechanism behind this optical switch in a protein found on the tentacles of a sea anemone. According to the researchers from the University of Pennsylvania, Drexel University and Harvard University, barium titanium oxide nanowires suspended in water could hold 12.8 million GB per square centimeter. If the memory density can be realized commercially, “a device the size of an iPod Nano could hold enough MP3 music to play for 300,000 years without repeating a song or enough DVD-quality video to play movies for 10,000 years without repetition,” the University of Pennsylvania researchers said.

Is the disk drive dead?

So, does this mean that the disk drive is dead in the future? I don’t think so. I believe that the disk drive we know and love will simply move from one tier of storage to another. We are already seeing some of this movement with the implementation is backup to disk. Technologies such as data deduplication will continue to accelerate this process, and the addition of new primary data storage technologies will simply end the process by pushing hard disk drives from on-line primary storage to what will be considered near-line storage in the future. Long live the disk drive!

About the author

Joerg Hallbauer

I am a long time data center denizen who currently focuses on storage and storage related issues. I have worked on both sides of the fence, for vendors as well as being the guy who had to impliment what they sold me. Finally, I've managed teams of UNIX, Windows, and Storage Admins.


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