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Next Wave Of Hard Drive Tech: Perpendicular Recording

Posted by timothy on from the dig-for-your-data dept.

angrytuna writes "New serial technologies are set to replace standard SCSI and ATA (Advanced Technology Attachment) interfaces over the next two years, even as hard-disk drive manufacturers prepare for an entirely new form of bit storage. Perpendicular recording will replace longitudinal recording in storage devices, placing bits on end instead of lying them parallel on the disc surface, thus dramatically increasing the possible storage density."

2 of 380 comments (clear)

  1. Re:Details? by Gogo+Dodo · · Score: 5, Informative
    Essentially, as I understand it, with longitudinal recording the poles of the bits are pointed flat on the surface. Imagine a bar magnet. Put the long flat end of the bar on the platter. That's longitudinal recording.

    With perpendicular recording the bar magnet would be standing on it's end.

    Longitudianl recording is like this:

    N--S
    ------------------- platter
    Perpendicular recording is like this:
    N
    |
    S
    ------------------- platter
    Google is your friend...
  2. What this MEANS by TwistedSpring · · Score: 5, Informative

    If you have no idea what the difference between Longitudinal Recording and Perpendicular Recording might be, and the phrase "stands the bits on end" meant absolutely nothing to you because its an utterly ridiculous way to explain it, here's the lodown. Longitudinal recording is what we use today in everything from cassette tape to hard disks. It works by magnetising tiny sections of the recording medium. You can imagine the magnetised sections as tiny bar magnets laid end-to-end. The read head detects transitions in the direction of the magnetic field.

    <- -> <-- -> <- -->

    In the above diagram we're looking down at one track on the surface of a platter. Perpendicular recording works differently. The "magnets" or bits are arranged so that the field they emit is perpendicular to the medium, like this:

    x . x . x . x .
    In the above diagram we're looking down at one track on the surface of a platter 'x' represents a field pointing away from us, '.' is one pointing towards us. This is what it looks like in cross-section (looking in from the edge of the platter):
    ^ | ^ | ^ | ^ | ^
    | v | v | v | v |

    In perpendicular recording the read head detects the actual direction of the fields emitted by these bits/magnets, rather than transitions in the field. Perpendicular recording is advantageous because it allows one to use a much smaller surface area on the medium for one bit. Imagine if you laid a line of bricks end-to-end on the ground, you could make the line shorter but taller if you stood each brick on end (so they're laid flat-to-flat), but you've not had to make the bricks any smaller in order to acheive this change in the length of your line.

    Most of the above is hopefully right. Anyway it's a better explanation than that site gave.