how does a hard drive work?

Answer 1

A typical hard disk drive design consists of a spindle which holds one or more flat circular disks called platters which spin at a high speed on a high quality bearing. Older drives used ball bearings, but newer drives use a fluid bearing for lower friction, lower noise and improved reliability.

The hard disk uses the rotating platters to store data. Each platter is coated with a smooth magnetic film structure on each side onto which digital data is stored. Information is written to the disk at high speed as it rotates past read-write heads that fly very close over the magnetic surface. The magnetic medium (film) on the disk surface changes its magnetization in microscopic spots due to the head's write field, which is a strong and highly localised magnetic field. The information can be read back by a magnetic sensor (a magnetoresistive (MR) or GMR read sensor) which is part of the same head structure on the trailing end of the flying slider. The read sensor detects the magnetic flux emanating from the transitions passing underneath it through a small change of the MR sensor's electric resistance and this is converted by electronics into a stream of 1's and 0's. Newer HDDs feature Tunnel Magnetoresistance (TMR) sensors, which function essentially in a similar way by changing electric resistance when detecting changes in magnetic field, but produce a stronger signal compared to GMR sensors.

There is one head for each magnetic platter surface on the spindle, mounted on a common arm. The actuator arm moves the heads on an arc (roughly radially) across the platters as they spin, allowing each head to access almost the entire surface of the platter.

The associated electronics control the movement of the actuator and the rotation of the disk, and perform reads and writes on demand from the disk controller. Modern drive firmware is capable of scheduling reads and writes efficiently on the disk surfaces and remapping sectors of the disk which have failed.

Also, most major hard drive and motherboard vendors now support self-monitoring, analysis, and reporting technology (S.M.A.R.T.), by which impending failures can be predicted, allowing the user to be alerted to prevent data loss.

Answer 2

Well something like Wikipedia probably puts it down to magnetic plates and tiny little electronic devices that look like tiny record players that move over the plates and read 1's and 0's but I suspect that's totally bollocks.

Its magical pixies, clearly. .. magnetic plates... read-heads... total balony....

obviously it's pixies!!

Answer 3

Search for it at wikipedia
www.wikipedia.com

Answer 4

hardly!