By 2011 we may see 4 Tb or larger external HDDs and 4-disk 3 TB
drives from all the major 3.5-inch drive manufacturers, according to Thomas M. Coughlin, the founder of Coughlin Associates.
Seagate Technology and Western Digital introduced external HDDs
with 3 TB storage capacity earlier this year. These 3 TB external
HDDs had 5 disks and so were thicker than HDDs for desktop
computers. Both Seagate's and Western Digital's 3.5-inch 3 TB external HDDs
used had 5 rather than 4 disks and so were too thick for most
internal computer applications. By adding an extra disk a HDD
company can increase storage capacity without increasing the
areal density (areal density determines the amount of bits that
can be stored on a disk surface). There is an overall trend to
increasing the component count in HDDs as the areal density
growth has slowed over the last year or so.
Small external HDD storage has become a significant driver of
disk drive volume. In the third quarter of 2010 Mr. Coughlin
estimates that close to 8% of all HDDs went into branded products
(Digital Storage Technology Newsletter, Coughlin Associates,
October 2010), mostly external storage devices. Because these
devices sit on desks or in pockets they don't have the same tight
constraints on dimensions that are necessary for HDDs that are
incorporated into computer products. For computer products the
hole or slot that they must fit into determines the product
dimensions. Thus adding extra components to achieve higher
capacities is easily done for external storage devices. At the
same time external storage devices are used for backup and higher
storage capacity are generally more attractive since they allow
backing up more content or devices.
For a true desktop computer with 3 TB storage capacity only a
maximum of 4 disks can be used. Thus higher storage capacity
requires higher storage capacity areal density. WD's 3 TB 4-disk
drive requires an areal density of about 530 Gbpsi (gigabits per
square inch). This product raises the bar on storage capacity and
we should see 3 TB desktop HDDs from all the major disk drive
suppliers by the first par of 2011, Coughlin Associates
estimates.
In 2011, besides widespread use of desktop storage technology
enabling 3 TB storage capacity earlier in the year, we might see
higher desktop capacities (depending upon the slowing rate of
areal density increases).
"At the very least we will probably see 4 TB or higher external
storage with small additional increase in areal density and using
5 disks," Mr. Coughlin said. "We expect that 2.5-inch external
storage will move beyond the 2 TB available today to as high as 3
TB and laptop 2.5-inch drives with 1.5- 2.0 TB could happen in
the second half of 2011 or early in 2012. Should Toshiba wish to
push the storage capacities of 1.8-inch HDDs it would be possible
to make one of these with 1 TB storage capacity," he added.
Beyond 2011 traditional perpendicular recording advances become
more difficult and dual stage actuator HDDs or drives for some
special applications using what is called shingle writing could
provide even higher areal densities while the HDD industry sorts
out whether HAMR or patterned media are the choice for more
significant and multi-generational HDD areal density advances.