Anatomy of hard-disk
- platters and double of heads of platters
- since we can use upper and lower of platter
- usually sector is 512 bytes
- head need physical take off and landing - slow
- Disk address = (driver, surface, track, sector)
- Cylinder-based mapping
- Seek time : The head is moved to the target track
- latency : Rotational latency
- Transfer time: Read/write the sector
Mapping algorithm or disk addressing
Mapping from sector address to logical block address
(surface j, track i, sector k) = k + s * (j + i*p)
- Assuming p surfaces in the disk and s sectors per track.