This month Hitachi announced and demonstrated at the CES the world’s first 3.5” terabyte disk drive. Note, a terabyte is 1,000 times 1 billion bytes or characters.  The drive is shown below.


It looks like any other 3.5” disk drive but inside it embodies the very latest in recording technology known as Perpendicular Recording.  It is the latest in the long string of ‘pulling the rabbit out of the hat’ innovations that have characterized disk drive technology.  On many occasions when it seemed that the limit of capacity and density had been reached someone would come up with a way to push the barrier further out and create a way to maintain the incredible rate of growth in capacity and performance that is the legacy of these devices. 

Last year we celebrated the fiftieth anniversary of the disk drive.  The first drive, developed by IBM, comprised 50 24” disks each one of which had the capacity of 100,000 alphanumeric characters of 6 bits each (the byte had not been invented yet) for a total of 5,000,000 characters.  The box housing the spindle, disks and access mechanism weighed 1.5 tons!  The new gigabyte drive has 26,000 times the capacity on 1/10th the number of disks in 1/11,000th of the volume and about 1/3,000th of the weight.  The new disk drive can access more data in a single operation than the entire contents of the original drive and do it in 1/60 of the time it took to find a single record.  All of this for 1/300,000th of the price!  We have come a long way; the question is how much further can we go.  Below is the original IBM 305 disk unit.


Before we try to answer that question let us look at perpendicular recording to understand how this latest improvement works.  The recording basics really have not changed since the beginning.  Magnetic spots are created on a rotating disk surface that can be detected by a magnetic pick-up known as a read head.  The spots are actually oblong on the surface of the disk along the direction of travel.  The read head senses the magnetic field of the spot and identifies it as either a digital 0 or 1 depending upon the direction of the magnetic field.  Over time ways were found to make the spots smaller and smaller and tracks closer and closer until it appeared that no further improvement could be made.

Looking at the illustration above, the dark arrows represent the magnetic spot son the disk looking at a cross section of the disk, with the pick-up sitting above the disk detecting the magnetic fields as the disk rotates.  The practical density limit of this approach was reached about 2 years ago. What to do?  Well it turns out that a Japanese professor; Professor Sun-ichi Iwasaki in 1975 came up with the idea of creating vertical magnetic spots instead of horizontal spots.  Sounds easy but it required a lot of hard work with materials, design and manufacturing techniques to make it work.  But finally all the problems were solved.  Below is the equivalent illustration for perpendicular recording.  As you can see,several spots can be squeezed into the same horizontal space as was achieved with horizontal recording.

So here we are with another great leap forward.  We should be able to squeeze another 2maybe 3 times the density of the new devices before we run into the wall again.  What then?

Unfortunately it appears that there are no more rabbits in the hat.  We are staring at the molecular limit of what can be done with the current technology.  We are now back to research looking at several different approaches to storing data, none of which bear any resemblance to our current devices.  Since these efforts are in research it is going to be several years before we know what the best solutions will be.  Several appear promising.  For sure, there will be something that comes along but today our vision is clouded.

So Ben Higginbotham, with respect to your pool, guessing when there will be a laptop with a 1 terabyte disk drive in it, I’m afraid I’m going to have to say “it’s not in the cards, at least not today”.