Pan platter heads for hard disks

[Siddhartha Jain]

Hey,

Me and my colleague were discussing the new PCI-Express architecture
and sighed at how HDDs still lagged far behind other peripheral
devices. But we both were curious about the same thing, that is, why
can't HDDs be made with a head platter over a magnetic media platter?

So instead of one head that moves over the HDD platter's surface, what
if there was a single big circular head platter for each surface
consisting of several heads? That would make mechanical movement in the
HDD redundant, seek times will be zero and throughput would improve.
Ofcourse, the costs would be much higher to integrate the extra
components and the size could also grow but there are several
applications that would greatly benefit from zero seek times and there
are several IT deptts that will pay a hefty premium to get such a HDD.
So is just tooooo expensive or impossible to engineer?

- Siddhartha

 

[keith]

On Fri, 26 Nov 2004 06:31:08 -0800, Siddhartha Jain wrote:

Hey,

Me and my colleague were discussing the new PCI-Express architecture
and sighed at how HDDs still lagged far behind other peripheral
devices. But we both were curious about the same thing, that is, why
can't HDDs be made with a head platter over a magnetic media platter?

Have you researched current drives?

So instead of one head that moves over the HDD platter's surface, what
if there was a single big circular head platter for each surface
consisting of several heads? That would make mechanical movement in the
HDD redundant, seek times will be zero and throughput would improve.

How are you going to get the pitch of your "heads" to be the same as the
pitch of the tracks? (Hint: HDDs use GMR heads, where 'G' = Giant) Even
stepping around this little problem, how do you align your "heads" with
the track. Current drives use the track itself as a servo feedback
mechanism to center the head on the track. If your "heads" can't move,
how do they center on the track?

Ok, you've solved these trivial problems... Now consider that
track-to-track head movement on current drives takes about the same
time as a head switch (still have to re-acquire track center on head
switch). What does it save you to have multiple heads on a surface?

Ofcourse, the costs would be much higher to integrate the extra
components and the size could also grow but there are several
applications that would greatly benefit from zero seek times

You want zero seek time? Buy solid-state drives.

and there
are several IT deptts that will pay a hefty premium to get such a HDD.

The evidence says you're wrong. There are solid-state drives, yet thay
haven't taken over the IT world. Yes, they are expen$ive, but they
*should* be everywhere if you were right.

So is just tooooo expensive or impossible to engineer?

Soo many assumptions, soo little engineeeering. But, you did get one part
right. Who wants to pay even a nanodollar per byte?

--
Keith

 

[Siddhartha Jain]

keith wrote:

You want zero seek time? Buy solid-state drives.

and there
are several IT deptts that will pay a hefty premium to get such a
HDD.

The evidence says you're wrong. There are solid-state drives, yet
thay
haven't taken over the IT world. Yes, they are expen$ive, but they
*should* be everywhere if you were right.

http://www.dbazine.com/ault6.shtml

Looks interesting. Seems like ten times more expensive but we all know
what economies of scale can do.

 

[nospam]

Robert Baer <robertbaer@earthlink.net> wrote:

Sounds like the idea was to have multiple *fixed* heads (via a
platter).
Then, by definition, the heads create and read their own tracks; no
servo needed or desired.

Trouble is heads are currently 3 or 4 thousand times wider than the tracks
they read. So instead of one head reading 100,000 tracks you might have 100
heads reading err, 100 tracks.

Given the huge reduction in capacity semiconductor memory would be cheaper,
faster, and more reliable.