Recently Hitachi announced their 1TB hard drive which is now on top of my must have’s list , but the product will be available only around 2nd quarter 2007 . I don’t see the trend slowing down anytime in the future and Storage technology pioneers like Hitachi , Seagate and Samsung have all had some exiting new announcements . The most impressive of them being PMR and Hybrid storage technology
All HDD’s store data in form of tiny areas of either positive or negative magnetization on the disk surface each of these areas represents a ‘bit’ which is the most elemental form of information, these bits are written as circular ‘tracks’ on the surface in a longitudinal fashion , one could visualise it as how bricks are laid for construction, but in a circular fashion .There are millions of bits on a single track and there are thousands of such concentric circular tracks on a hard disk surface. The amount of data that can be stored depends on the Areal density per square inch of the disk. Areal density is defined as the number of bits/ inch (along the track) * tracks/ inch (radially on the disk) , the data capacity of a HDD is directly proportional to the areal density, advancements in storage technology have till now been primarily focused on increasing this parameter, but in recent times it has become exceedingly difficult to increase areal density by conventional methods because the magnetic material on the disk surface is composed of small grains, each bit written on the disk must cover about 100 grains to ensure that the information is reliably stored, the catch is that there is a lower limit to the size of these grains, below this limit data integrity is compromised in normal working conditions.
In perpendicular recording, the ‘bits’ point up or down perpendicular to the disk surface as opposed to the conventional method of bits being aligned longitudinally, visualize this as a lot of bricks placed on their smaller ends one atop another to form a tower of bricks , these images from Hitachi illustrate this better
this allows more bits to be squeezed in the same amount of space , PMR disks offer higher data capacities at increased speeds and are inherently more robust than their traditional counterparts.
Hitachi GST is the intellectual property leader in PMR and their website has more detailed information about PMR and other research projects, for a fun and interesting look at PMR click here. I ll be writing about hybrid storage as soon as i get some more insight about it , for some basic information visit the hybridstorage forum