in 1532937 20161025 103105 pamela wrote:
On 22:00 24 Oct 2016, Vir Campestris wrote:

On 24/10/2016 19:49, John Rumm wrote:
SNIP
Now in the case of a HDD there *may* be a relatively close
mapping of LBAs to physical sectors, such that as you step
through sequential LBAs it maps that to a physical address
efficiently - addressing adjacent sectors first, then heads,
and finally cylinders. However even here there is scope for
redirection since the drives support bad sector remapping etc.
So two sequential LBAs may actually be stored in completely
different areas of the disk even with a HDD.
/SNIP
While logically adjacent sectors may be away off in the spares
they're not likely to be. I don't think I've ever seen as many
as 1% faulty disc. You can assume that most of the time they'll
be next to each other.

Way back in the 1980s we had a report from QA that the new
faster disc drives were running slower than the old ones. On
closer examination this turned out to be one of the machines
only. And it had a spare track in the middle of the directory...
which with CP/M is the _only_ directory...

Modern systems have lost the stuff we used to do, where we'd
fiddle with the interleave for performance, not have sector 1 in
the same place on each track, or skew the sectors across
cylinders so a seek took you to the new track just at the right
place to sync up and read.

(not all at once!)

Andy

Hi Andy. I once did a bit of work with some hard drive developers
over in Havant (initially IBM then Xyratex then Seagate). I wonder
if you ever crossed paths with them or maybe even worked there?

After making all sorts of promises to the workforce, Seagate has now
decided to close Havant Plant.