Terabyte

4 Key excerpts on "Terabyte"

• 

  eBook - PDF

  TechnoSecurity's Guide to E-Discovery and Digital Forensics

  A Comprehensive Handbook

  • Jack Wiles(Author)
  • 2011(Publication Date)
  • Syngress

    (Publisher)

  T IP As media storage continues its rapid growth, investigators find themselves examining Terabytes of data. A Terabyte, for perspective, is 2 40 , or 1,099,511,627,776, bits. Each Terabyte represents about 500 billion pages of www.syngress.com Forensic Examination in a Terabyte World• Chapter 5 131 plain text—an amount that is staggering even to the most tenacious legal team. A petabyte, the next step up, equals 2 50 , or 1,125,988,906,842,624, bits. N OTE Legislation such as the Sarbanes-Oxley Act of 2002 adds to the storage volume problem as it requires companies to keep all records and data pro-duced. To complicate matters, not all aspects of storage are growing at a comparable rate. Similar to Moore’s Law is Kryder’s Law, named after Dr. Mark Kryder, senior vice president of research and chief technology officer at Seagate Corporation. Kryder’s Law tracks the progression rate at which hard drives grow, holding that magnetic disk storage density dou-bles annually, a more aggressive calculation than even Moore’s Law for transistors.This theory has held true from 1995 to the present, with growth rates actually increasing after the advent of institutionalized strategic technology reinvestment. T IP Based on the rate of hard-drive growth set forth by Kryder’s Law, we can expect to see 5TB drives in home PCs by 2011. N OTE When does too much data excuse a party from finding evidence? When the costs of analyzing data grow too high, who will pay? Currently, courts in the United States are debating whether to allow a responding party to avoid providing discovery of electronic data that is “not reasonably accessible because of undue burden or cost.” 1. www.syngress.com 132 Chapter 5 • Forensic Examination in a Terabyte World Distributed Computing Solution Most hard drives now contain in excess of 1 million file items.

  Sign up to read

  Learn more about book
• 

  eBook - PDF

  The Silicon Web

  Physics for the Internet Age

  • Michael G. Raymer(Author)
  • 2009(Publication Date)
  • CRC Press

    (Publisher)

  2.8.1 Bits, Bytes, and Other Units The basic unit of information is the bit. One byte is defined as 8 bits and is abbrevi-ated as B. For example, you might ask a salesperson how much memory a particular memory device has, and the response might be “1,000 bytes.” This is the same as 8,000 bits. When the number of bits is much larger, we use other units—the kilobyte (kB), megabyte (MB), gigabyte (GB), and Terabyte (TB). Recall that according to the standard metric system definitions, 1 the prefix k means 10 3 , M means 10 6 , G means 10 9 , and T means 10 12 . In common computer science usage, however, these symbols are often “misused” to mean 2 10 , 2 20 , 2 30 , and 2 40 , respectively. This usage arose out of the desire to have slang names for these quantities, and because of the near correspondence between the values: 10 3 = 1,000 whereas 2 10 = 1024; 10 6 = 1,000,000 whereas 2 20 = 1,048,576; 10 9 = 1,000,000,000 whereas 2 30 = 1,073,741,824; etc. Throughout this text, we will use the standard base-ten definitions of k, M, G, and T, except where otherwise noted. For example, when we write GB, we mean 10 9 B or 10 9 bytes. THINK AGAIN Given a hard drive that can store 40,000,000,000 bytes, some computer sell-ers might state that it can store 40 GB, whereas another seller using a differ-ent definition for G might state that the same hard drive stores 37.25 GB. THINK AGAIN The word bit is used here in two different ways. Bit can mean a binary digit, 0 or 1. Bit can also mean the basic unit of information. 1 The international standards for the physical sciences and for commerce are set by the International System of Units, abbreviated SI units from the French name Système International d’Unités. Although this system does not mention bits and bytes, it is clear on the meanings of the prefixes k, M, G, and T. Because of the potential confu-sion, a set of new binary prefixes for bits and bytes was introduced in 1998 by the International Electrochemical Commission (IEC).

  Sign up to read

  Learn more about book
• 

  eBook - ePub

  The Tao of Computing

  • Henry M. Walker(Author)
  • 2012(Publication Date)
  • Chapman and Hall/CRC

    (Publisher)

  In this system, 00000000 represents the decimal number 0, 00000001 represents the decimal number 1, 00000010 represents the decimal number 2, and so forth. Following this pattern, the largest binary number would be 11111111 or 128 + 64 + … + 2 + 1 (decimal) or 255. Altogether, this approach allows us to store the integers 0 through 255, inclusive, for an 8-bit number or byte; and we can conclude that one byte of data can take on 256 different values. Of course, this range is adequate for some data storage purposes in computers, but not for others. The 8-bit number with a range of 256 alternatives will arise several times later in this chapter and throughout the book.

  GROUPING DATA

  In computing, as well as in other fields of science, it is common to use a prefix to specify the size of a collection of data:

  • Kilo (K): thousand (or sometimes 1024 = 210 )
  • Mega (M): million (or sometimes 1,048,576 = 220 )
  • Giga (G): billion (or sometimes 1,073,741,824 = 230 )
  • Tera (T): trillion (or sometimes 1,099,511,627,776 = 240 )

  Thus, 2,097,152 bits (2 times 1,048,576 bits) is called 2 megabits or 2 Mbits, and 3,758,096,384 bytes (3.5 times 1,073,741,824 bits) are called 3.5 gigabytes or 3.5 Gbytes.

  Note: In many scientific applications, the terms kilo, mega, giga, and tera refer to powers of 10 (e.g., thousand, million, billion, and trillion, respectively). However, as described in Chapters 2 and 3 , much work in computing uses binary numbers, and sizes are therefore given in powers of 2. As 210 = 1024 is about a thousand, it is common for computing descriptions to write “kilo” for “thousand,” but mean 1024. Similar comments apply to the terms mega, giga, and tera.

  As binary numbers provide an effective way to represent data in computers, this approach is widely used. Data stored this way is often said to be digital.

  What other approaches can be used to store data, in addition to “digital” data?

  When we first discussed the representation of data in the previous question, we mentioned two main approaches for representing numbers. The first approach, using digital storage, involved binary digits: 0 and 1. In this approach, data (e.g., numbers) were translated into a sequence of 0s and 1s (e.g., the decimal number 77 was represented as the binary number 01001101). Within electrical equipment, a 0 might be translated to a circuit with no voltage or electrical current, and a 1 might be translated to a circuit in which current was flowing or voltage was set above 1.7 volts. This approach is called a digital

  Sign up to read

  Learn more about book
• 

  eBook - ePub

  Software-Defined Data Infrastructure Essentials

  Cloud, Converged, and Virtual Fundamental Server Storage I/O Tradecraft

  • Greg Schulz(Author)
  • 2017(Publication Date)
  • Auerbach Publications

    (Publisher)

  There is a hierarchy of bits and bytes along with how they are organized and built upon with additional layers to create and define their functionality. These bits and bytes are addressed and accessed by the processor running or executing the program code (algorithm) to do various tasks. The more bits there are, the more addresses or ability to define things to do or represent different data and information are available.

  Here are some bits and bytes basics:

  • Data is represented in binary (0’s and 1s, that is, base 2) format.
  • A bit is on or off (binary) and can be grouped into bytes.
  • 8 bits make a byte; a byte makes an 8-bit word.
  • Words can be larger than 8 bits (16, 32, 64 bits).
  • Be careful to avoid confusing bits and bytes: Big B for Bytes, little b for bits.
  • Various character encoding schemes and bits are used.
  • American Standard Code for Information Interchange (ASCII) includes 7-bit and 8-bit character encoding
  • Unicode includes 8-bit UTF-8, which incorporates ASCII.
  • Extended Binary Coded Decimal Interchange Code (EBCDIC) is an 8-bit character code used mainly on IBM mainframe operating systems.
  • Bytes get grouped into pages, blocks, sectors, extents, and chunks of memory (storage) of various size ranging from 512 bytes to thousands of bytes in size.

  The International System of Units (SI) is used for describing data storage and networking in base 2 format (see Table 3.3 ). For example, 1 GiBi (Gibibyte) = 2 A 30 bytes or 1,073,741,824 bytes.

  Table 3.3 Storage Counting Numbering and Units of Measures

  Another common unit of measure used for data storage and servers as well as their operating systems is gigabytes (GBytes or GB) in base 10 (decimal) format. One GByte represents 10 A 9 or 1,000,000,000 bytes.

  3.2.2 Where Are My Missing Bytes?

  Computer memory is typically represented in base 2, with disk storage often being shown in both base 2 and base 10. For example, the SSD that I used in my laptop while writing this book is advertised as 512 GB. Before any operating system, RAID, erasure code, or other formatting and overhead, the SSD presents itself as 476.84 GB.

  Sign up to read

  Learn more about book