This page allows to play around with some calculations.
Sustained Data Rate
File Size / Fragmentation
This section shows how the maximum sustained
data rate results from the main parameters RPM and
sectors per track, together with the timing.
Values for head skew and cylinder skew are hard to find, so
the values used in the examples are just guesses.
This is a simplified calculation to show
the impact of seek, latency, fragmentation and file size.
The faster the harddisk and the smaller the file or
fragment size, the more time is lost due to latency and
At 85MB/s, a 100kB file is transferred in 1.15ms.
One full revolution of a 10,000RPM harddisk takes 6ms,
one full stroke of the WD Raptor takes 10.2ms. Even
assuming that the filesystem information is already cached, it
can still take up to 16.2ms just to get the head
to the first sector of the data!
This is the calculation from the Samsung HD501LJ and
Seagate Barracuda 7200.8 SATA analysis.
The calculation assumes a maximum transfer rate
where all head and cylinder switches succeed, and
calculates the values for a certain amount of