(Or sector map) The mapping from logical to physical sector
numbers on a magnetic disk designed to optimise sequential
reads and writes. Data is usually transferred to and from the
disk in blocks or sectors where one sector lies within a
continuous range of rotational angle of the disk. If logical
sectors are assigned sequentially to physical sectors
(0,1,2,...) then by the time one sector has been read and
processed (e.g. writen to main memory) the start of the next
logical sector will have passed the read/write head and will
not be accessible until the disk's rotation brings it back
under the head.
Staggering the physical sectors (e.g. 0,3,6,1,4,7,2,5,8) aims
to allow just enough time deal with one sector before the next
is accessible. This obviously depends on the relative speed
of the rotation of the disk, sector size, sectors per track
and the speed of transfer of sectors to main memory.
Nearby terms:
second normal form « Second-Order Lambda-calculus « second-system effect « sector interleave » sector interleaving » sector map » sector mapping
