=Introduction=
Here is a big mess, or even a tangled web… What are the differences between GB, Gb, Go, Gb/s, Gbps, and why on earth is 10% missing from my hard drive?
=Abbreviations=
We work every day in computing with a whole bunch of abbreviations. Here are some explanations to help you make sense of them.
==Data Abbreviations==
- “b” is not equal to “B” or “o”
- b = bit. (pronounced “bit”) English word meaning “character”. Bits are “0” or “1”
- B = Byte (pronounced “bite”). English word meaning “word”. The Byte can contain 7 or 8 characters. But in the case that interests us, in modern computing, everything is based on 8.
- o = Octet: This is the French translation of Byte, nothing more, nothing less
==Quantity Abbreviations==
In everyday life, Kilo = thousand, Mega = 1 million, Giga = 1 billion. Easy.
In computing, Kilo = 1,024, Mega = 1,048,576, Giga = 1,073,741,824. I’ll spare you Tera and Peta, but take Giga and multiply by 1024 for Tera, and again by 1024 for Peta.
==”Composite” Abbreviations==
In computing, we talk about network bandwidth in bits and capacity or transfer rate in Bytes. It’s probably historical. But I’m not a historian ([http://www.google.com Google] is your friend).
In the world of networking, for example, ADSL or 3G, you will be sold access in Megabits per second. Mbps or Mb/s (Mega bits per second).
When you buy a hard drive, for example, you will be sold a SATA drive with a capacity of 500GB (GigaBytes) and a transfer rate of 150MB/s (MegaByte per second).
=Loss of Capacity or Bandwidth=
But the most curious among you will have noticed that when they check the capacity of their hard drive (on Windows, right-click on C: in My Computer, then “Properties”), the capacity does not match the one promised when you ordered the computer or hard drive.
==The Truth About Hard Drives==
The truth is that marketing teams have been at work. 1024 has become 1000 for them. But in reality, it’s the opposite. Basically, here’s the marketing calculation:
- 1 Byte * 1000 = 1KB * 1000 = 1MB * 1000 = 1GB * 1000 = 1TB = 1’000’000’000’000 (1 trillion) Bytes
In physical and technological reality:
- 1’000’000’000’000 Bytes / 1024 = 976562500 KB = 953674.3 MB = 931.32 GB
A “marketing” 1TB hard drive is therefore only 931GB in reality.
==The Truth About ADSL or vDSL==
Here too, marketing teams have had a field day, using the same trick, thus saving significant bandwidth across their vast number of customers.
If your connection is, like mine, advertised at 5Mb/s (Mega bits per second), it actually only runs at 5000Kb/s and not 5120Kb/s as one might expect.
There may be a particular reason in the networking world for a base of 1000 instead of 1024. I haven’t looked into that level of detail.
Petite erreur :
Un disque dur de 1Go “marketing” ne fait donc que 931Go réels.
1To non?
En effet 🙂 Merci, c’est corrigé.