We're approaching the 50th anniversary of the magnetic
hard disk drive, so a technology that's been
around for five decades, in different incarnations, is still
going strong. Recently, we saw the introduction of the first 1
terabyte (TB) hard disk drive.
@36263 Perpendicular recording has been an important technology.
In the past, data was laid down (or magnetized) in a horizontal
format where it took up more surface area on the platter. Now the
data is laid down vertically, or on end, where it takes far less
surface area, improving data density and allowing more data to be
stored in the same physical area known as aerial density.
We're seeing disk drives of various capacities, speeds and form
factors, and this can lead to confusion. For example, most
enterprise drives shipping today are 3.5-inch form factor using
SAS,
SATA,
Fibre Channel and even traditional
PATA) disk interfaces. The problem is that not
all 3.5-inch disk drives are high-performance drives. Some are
high capacity SATA drives, some are high performance 15,000
revolutions per minute Fibre Channel or SAS drives. Enterprise
high-performance small 2.5-inch form factor drives are also
appearing, and this is also causing confusion. Traditionally,
the 2.5-inch drives have been used in small devices, like
desktops and laptops/notebooks, but a new generation of 2.5-inch
10,000 to 15,000 rpm high-performance SAS drives is available.
Form factor is no longer indicative of technology or
performance.
And more improvements are on the horizon. As the drives get
smaller, they can spin faster while putting more data in the
smaller footprint -- this translates to larger capacity and better
performance. But, hard disk drives are also reducing their power
consumption with multiple power settings and adding other
functions, such as encryption at the drive level. The recent
introduction of "hybrid drives" add significantly more memory to
complement the mechanical drive, effectively caching more of the
drive's data to memory and allowing the mechanical device to power
down more frequently. For example, some drive vendors are releasing
32 GB or 64 GB SATA drives with flash memory only (solid state).
We're also seeing variations that combine physical disk with flash
or RAM memory. For example, Seagate Technology released a drive in
2006 that combined all three elements -- think of it as real
"tiered storage" right on the disk drive itself.
Another innovation is referred to as "sleepy drives" that
throttle back the revolutions per minute, reduce power consumption
or otherwise power down to some extent when not being used. This
technique reduces power consumption, which saves money and can
improve battery life in laptops or other mobile devices.
Some experts expect magnetic hard drive technology to remain
viable out to 2015 or even 2020.
Go back to the beginning of the
Disk Hardware FAQ Guide.