13 Jan
2011
13 Jan
'11
4:39 p.m.
Couldn't find original sender:
Except for a few very odd ones (e.g. hard drives
which record =
analagoue
singals such as analogue video [1]) every hard
disk I've worked on has
used both sides of all platters for something. Maybe not user data
storage (for excample, it may contain servo information only), but =
there
will be a head on it.
Because of the enormous pressure to reduce cost, single headed drives =
are very common. And have been for as long as I've been in the HDD =
industry. For example, current technology is 667 or 750 GB per platter =
with 1TB/platter due in next 12 months. Yet there is a demand for 250, =
300 or 500 GB drives for ultra low cost drives. Especially in the =
consumer electronics market - for example, DVRs and security systems.
Taking out the cost of one head can save $2.50 to $5.00 of manufacturing =
cost. That is a big chunk of the $25 manufacturing cost typical of the =
very low end drives.
Servo data has been embedded in the data surface for many many years. =
Most current drives generate their own servo information. Current =
drives even have a different tpi for the servo versus the data track, =
even though they are on the same surface.
Billy Pettit