IEEE Consumer Electronics Magazine - July 2016 - 124

WHAT GOOGLE WANTS iN HDDs
HDD Shiments in Millions of Units

200
Performance Enterprise
Capacity Enterprise

180
160
140
120
100
80
60
40
20
0

2010 2011 2012 2013 2014 2015 2016 2017 2018 2019 2020

FiGurE 5. The growth of capacity versus performance enterprise HDDs, according to
Coughlin Associates (February 2016).

are being developed that provide higher
storage capacity in a given form factor
HDD. In particular, HGST Inc., a WD
division, introduced HDDs for enterprise storage applications that are hermetically sealed and contain helium
(He), rather than air. With this technology (Figure 4), He in the drive is much
less dense than air, thereby reducing
the resistance to disk rotation, allowing
thinner and more disks in an HDD and
aiding in reducing the heat generated
by the HDD during operation. Handling the heat generated by storage and
processors in modern data centers is a
large part of the overall operating cost,
so less heat means lower cost storage.
The remaining HDD companies
plan to follow HGST's lead with Hefilled HDDs for cold-storage enter-

We project that the decline
in performance HDDs will
continue as these drives are
displaced by solid-state drives
(SSDs), whereas high-capacity
storage using HDDs will be
increasingly used in large
data-center storage pools.
prise applications. Seagate announced
its first He-filled drive in early 2016
with 10-TB capacity. These drives are
some of the most popular products for
HGST and may become the dominant
bulk storage devices used in cloud
storage applications.

YouTube Upload Rate

h/min

100

1
2006

2008

2010

2012

2014

2016

FiGurE 6. The increase in the rate of uploads to YouTube from 2006 to 2015.
124 IEEE Consumer Electronics Magazine

JULY 2016

Although high-performance 10,000 and
15,000 r/min HDDs have been in unit
shipment decline since 2013, HDD
units that provide high capacity for
storage arrays have been growing, as
shown in Figure 5, and now exceed the
performance drives. We project that the
decline in performance HDDs will continue as these drives are displaced by
solid-state drives (SSDs), whereas
high-capacity storage using HDDs will
be increasingly used in large data-center storage pools.
A recent Gartner -Stifel estimate
shows that revenues for enterprise
HDDs and SSDs will cross over in
2017. This may be consistent with a
move from using performance HDDs
to SSDs and enterprise HDDs, focusing more on capacity. Overall, HDD
shipments for enterprise applications
are expected to increase, as are HDDs
for external storage and consumer
applications in 2016. On the other
hand, we expect a gradual decline in
HDDs for personal computers in
2016 and later as the size of SSDs
increases and price decreases, making
them an attractive option for many
computer users.
Eric Brewer and colleagues from
Google argue that with the growth in
portable devices and services in the
cloud, hard disks will be deployed primarily as part of large storage services
housed in data centers. As a result of
the growth of data-center data on
HDDs, Google advocates some changes in their design.
YouTube users upload more than
400 h of video every minute. At 1 GB/h,
this results in a petabyte of new storage
every day. As Figure 6 shows, the trend
for video uploading is increasing exponentially by about tenfold every five
years. Most of this new video is stored
on HDDs.
Three differentiators for HDDs are
used in data centers. The first focuses
on aggregate properties of the collection of HDDs. The second focuses on
tail latency derived from the use of
these HDDs providing live services.
The third important factor is the various
security requirements resulting from

Table of Contents for the Digital Edition of IEEE Consumer Electronics Magazine - July 2016