[Sussex] Hard drive question

[Steven Dobson]

John

On Fri, 2006-10-27 at 17:40 +0100, John Crowhurst wrote:
> On Fri, October 27, 2006 17:04, linux at oneandoneis2.org wrote:
> > Hard drives with multiple platters & therefore multiple heads: When
> > writing to the disk, is only one head active at a time, writing the
> > whole file to one platter; or do all the heads write at once, with
> > head one writing the first bit of the file, head two writing the
> > second bit, and so on?
> 
> Hard drives are accessed randomly, so one of the heads accesses the drive
> on one platter. The file will be scattered over the different platters as
> the drive writes in its most optimum pattern.
> 
> Drives don't 'fill' one platter before moving to the next, the data fills
> up  in a pseudo random manner.

While what you say is true I am worried that you give the impression
that the different blocks of a file will be scattered randomly over the
disk.  This is not the case.  File Systems go to a lot of trouble to
group the different blocks of a file close together so the file is
quicker to read back.

Steve
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