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Technical
problems are causing headaches in the quest for ever-faster hard disk
platters.
Sick
of waiting
for your PC to rip a load of MP3s
or do a batch file conversion? As CPUs
and memory get faster, CPU cycles are going to waste while your PC
makes I/O
requests to your hard disk.
One obvious solution is to increase drive speed,
but increasing
revs per minute from
the glass disk platters is proving
difficult. Experts suggest
drive speeds will max out at 15,000rpm,
compared to
7,200rpm in most PCs today.
"We
don't expect them to go beyond 15,000rpm
—there's no point," said IDC storage analyst Graham Penn.
Spinning
a disk at high speed within the tight
confines of a drive bay isn't as easy as it sounds. As disks spin
faster, they
generate problems that include extra heat, wear on the motors and
bearings,
and
pressure variations within the drive.
Increased
storage density in newer drives means
that bits are
packed more closely together making them harder to read at high speeds.
This
speed versus density trade-off means that
higher speed drives are
increasingly
expensive to produce.
This
isn't to say that vendors aren't experimenting with higher speeds.
"We've
actually looked at a 23,000rpm product," said Seagate global
representative Michael Green, "but no-one wanted it. It was just too
expensive [to produce]"
Users
may not realise how weak a link
in the speed chain the  hard
drive can be, especially taking factors
such as the
wait for
the
drive head to move to the right track on the disk into
consideration. 7,200rpm disks have a
seek time and latency of 8.9
milliseconds, during which time 26 million clock cycles can go to waste
on a
3GHz CPU while the head of the drive is just getting to the right
position to
read data from the disk. To us, that 8.9ms goes faster than the blink
of an
eye, but to a CPU it's an eternity.
For
the moment,
the strategy of
drive manufacturers is to keep increasing
storage
densities
while keeping drive speeds relatively stable. According to figures from
Seagate, "real" density jumps 60% every six months. New
I/O
technology like SATA2 and vertical rather than horizontal packing of
the magnetic strata on drives will also
help alleviate some latency by
improving bandwidth to and from drives.
Eventually
experts say drives with
15,000rpm speeds will migrate from
expensive
SCSI servers to
ordinary desktops, but after that latency pressures may make drive
manufacturers look for a new solution. William
Maher and Jarrod Spiga
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