Magnetic Storage Flashcards
What is magnetic storage
Storage medium where the disk surface is coated with minute particles of Ferric Oxide 9rust) which are polarised by a magnetic field.
What is a Hard Disk Drive
A Drive used to hold data on hard and inflexible platters. Can be internal and external.
What is a HD Head Float
The Head floats above the disk surface on a cushion of moving air which is created by the disk spinning. 0.0003mm
What is the Read/Write head?
An Electromagnetic coil used to read or write data to the disk.
How do you read data from a HDD
A coil is passed over the surface and the magnetic domain on the surface induces a current in the coil.
How is data written to a HDD
A magnetic field is created to change the alignment of the particles. Done by passing a current through the head coil in one direction or the another.
What is the landing zone?
The unused area in the centre of the platter where the heads park.
What is a Head Crash?
When the head touches the disk surface whilst spinning, due to vibration / shock. Ferric oxide coating is scratched creating bad sectors and in severe cases damages the heads.
What are bad sectors?
Parts of the disk what can no longer hold data. Shows up as a CRC error
Automatic Sector translation
aka bad sector remapping. HDD have extra sectors which are used to replace any bad sectors.
What are platters?
The disks that the data is written onto. Usually doublesided.
What is Hermetically sealing?
Completely sealed.
What is CAV?
Constant angluar velocity - disk spins at the same number of revolutions per minute all the time.
What is a Disk track?
The disk surface is marked out into circular tracks one inside the other.
What is a Sector?
A part of the track.
