• 1 Exabyte (EB) - 50,000 years of stored DVD-quality video. As of early 2013, it was estimated that
there was over 1 Exabyte of data files stored in the
Cloud7 and about 21 Exabytes of data flowing through
the Internet each month. 8
• 1 Zettabyte (ZB) – is equal to 1 billion Terabytes
and represents approximately 36 million years of stored
HD video. 9 Recently it was reported that the National
Security Agency facility located in Utah will be able to
store 5 Zettabytes of information. 10
Regardless of how it is expressed, a Zettabyte is a lot
of data, all of which has to be created, captured, and
stored somewhere, generally on computer or server
HDDs. However, there are potential pitfalls on the
horizon as current computer HDDs and storage technologies may not be able to keep up with the increasing
demand. Indeed, Moore’s law may no longer be valid
by the end of this decade due to the fact that there are
physical limits to the further miniaturization of transistors. About 75% of the data in the digital world is
generated by individuals. 11 This fact alone will continue
to drive the demand for both increased processing power and storage capacity. Regarding storage capacity, the
ubiquitous HDD is still the most prevalent device in use
today for both short and long term data storage. HDDs
provide an efficient and cost-effective way to manage
large amounts of data.
Very Brief HDD History
The first commercially available HDD was manufactured by IBM in 1956 for their RAMAC 305 system.
Consisting of 50 two-foot diameter disks spinning at
1200 revolutions per minute, it was the size of two
refrigerators and stored a total of 5 Megabytes of data. 12
(That’s about the size of one of today’s typical MP3
encoded music files!) Early HDDs were used primarily
as external storage devices for mainframe computer
systems commonly found in governmental agencies and
large corporations. IBM introduced the predecessor of
today’s HDDs (those with sealed assemblies, lubricated
spindles, and low-mass heads) in 1973.13 Personal computer growth in the late 1970s and early 1980s exponentially increased the demand for internal HDDs. The
development and standardization of IDE technology
during the 1980s eventually led to uniform HDD sizes
and shapes ( 5. 25”, 3. 5”, 2. 5”, and 1” form factors).
Since their development, HDDs have evolved into
relatively small, inexpensive devices with extremely
fast access times and huge amounts of storage capacity.
The two primary characteristics of all HDDs are their
storage capacity and performance. As we have previously seen, capacity is expressed in powers of 1000: a 1
Terabyte HDD contains 1012 bytes. However, not all of
the bytes on a HDD are available to the user. The file
system (FAT, NTFS, etc.), the computer operating system, inbuilt redundancy for recovery, user applications,
hidden partitions, and so on can use considerable space
on a HDD. Average Access Time (the time it takes the
heads to move to a file) plus the Average Latency (the
time it takes for a file to move under its head) and the
Data Rate (the speed at which the file is transmitted) all
effect HDD performance.
This discussion will continue in a future column.
with-open#awesm= ~oagw9E80 sq Pzth.
3. “IDC Predicts 2012 Will Be the Year of Mobile and Cloud Platform Wars as IT Vendors Vie for Leadership While the Industry
Redefines Itself.” IDC. 2011-12-01.
5. “NASA - NASA - The Hubble Story.” Nasa.gov. 2010-04-29.
6. Kane, Zee (January 1, 2010). “Believe it or not: Avatar takes
1 Petabyte of storage space.” Thenextweb.com.
11. Gantz, John and Reinsel, David. “Extracting Value from
Chaos,” June 2011.
John J. Barbara owns Digital Forensics Consulting, LLC,
providing consulting services for companies and laboratories
seeking digital forensics accreditation. An ASCLD/LAB
inspector since 1993, John has conducted inspections in
several forensic disciplines including Digital Evidence. jjb@
Read more Digital Forensic Issues