SAMSUNG HARD DISK DRIVE
Data is recorded on lots of circle in media in HDD, we call these circles track.. We record data
at both sides of media and HDD has many media layers. so it has several tracks which have
the same radius, we call this concentric circle collection of track Cylinder. Tracks are divided to
sector and it organized ID information and data and ECC. ID information is a sort of address
information to seek data sector requested from host computer.
Separate complex data/clock signal from HDD stored data/timing information encoded form.
Restore encoded signal.
Concentrate servo signal (Timing & location control signal) on on side of drive.
Find defect and treat data from replaced sector on read/write.
HDD vendor received disks from media vendor for smooth supply and proper price and these
media has defect( region can't read write data), by scanning defect during production process
and replacing normal region so we can product defect-free drive. Defect management means
scanning defect and treatment process from replaced data during read/write.
Head record data in this circle plate, magnetic disk is general.
Group assembled the separate HDD for large capacity.
Direct Memory Access, data transferring method among system memory and HDD without CPU.
By using DMA, CPU can do other works while data transferring, efficiency become improved.
dead on arrival, arrival failure.
Defect parts per million, failure unit.
Functional definition according to the numbers of head,cylinder,sector per track.
Design Verification test.
Error correction code. Correct error data, controller scan and correct error combining user data
and parity bit.
ECC is Error Correction Code, Additional recording information per every sector. By ECC
creation logic, data is added on disk and checking and correcting with reading. If it is
correctable error without read action stopping, we call this ECC on-the-Fly with hardware's help
Revised interface in IDE way, new specification to improve the existing method has problem of
Embedded Servo: Arrange servo signal(timing,location control signal) to data and data track in
Encoding is a data transferring method before recording data pattern to disk and Decoding is on
the contrary. To read recorded data more easily and accurately, Encoding and Decoding should
be needed. Coding methods are MFM.(2.7)RLL.(1.7)RLL.
Dedicated Servo: Mechanism of dedicated surface of disk have timing and positioning