Ext HDD question

[beamish]

I've just bought the FreeAgent Go 320Gb to take with me to Kielder etc and on opening up Seagate manager and drive info I find that the capacity of the drive is 298.1Gb and free is 297.5GB.

Now call me old fashioned but if this is a 320Gb HDD where are the other 21.9GB????

Isn't this mis-representation under the sale of goods act , trade descriptions etc ??? Can someone offer a reasonable explanation ?

[Euan]

I was going to explain it but Wiki does it better

Consumer confusion

Since the early 2000s most of consumer hard drive capacities are grouped in certain size classes measured in gigabytes. The exact capacity of a given drive is usually some number above or below the class designation. Although most manufacturers of hard disk drives and flash-memory disk devices define 1 gigabyte as 1000000000bytes, software like Microsoft Windows reports size in gigabytes by dividing the total capacity in bytes by 1073741824, while still reporting the result with the symbol "GB". This practice is a cause of confusion, as a hard disk with a manufacturer-rated capacity of 400 gigabytes might be reported by the operating system as only "372 GB", for instance. Other software, like Mac OS X 10.6[2] and some components of the Linux kernel[3] measure using the decimal units.

In the Content Delivery Network industry, where billing is often done by the Gigabyte, there can be a difference up to 7% between vendors based on the definition of the size. Some companies including 3Crowd and BitGravity, have referenced agreed upon definitions for 1024 Megabytes multiplied by 1000 as a Barretbyte GbB, referencing BitGravity co-founder Barrett Lyon for billing purposes.[4]

The JEDEC memory standards uses the IEEE 100 nomenclatures which defines a gigabyte as 1073741824bytes (or 230 bytes).[5]

The difference between units based on SI and binary prefixes increases as a semi-logarithmic (linear-log) function—for example, the SI kilobyte value is nearly 98% of the kibibyte, a megabyte is under 96% of a mebibyte, and a gigabyte is just over 93% of a gibibyte value. This means that a 300 GB (279 GiB) hard disk is indicated only as 279 GB. As storage sizes increase and larger units are used, this difference becomes even more pronounced. Some legal challenges have been waged over this confusion such as a suit against Western Digital.[6][7] Western Digital settled the challenge and added explicit disclaimers to products that the usable capacity may differ from the advertised capacity.[7]

Because of its physical design, computer memory is addressed in multiples of base 2, thus, memory size at the hardware level can always be factored by a power of two. It is thus convenient to use binary units for non-disk memory devices at the hardware level, for example, in using DIMM memory boards. Software application, however, allocate memory, usually virtual memory in varying degrees of granularity as needed to fulfill data structure requirements, and binary multiples are usually not required. Other computer measurements, like storage hardware size, data transfer rates, clock speeds, operations per second, etc., do not depend on an inherent base, and are usually presented in decimal units.

[ponytale]

seagates answer : When referring to hard drive capacity, one gigabyte, or GB, equals one billion bytes and one terabyte, or TB, equals one trillion bytes.

Your computer’s operating system may use a different standard of measurement and report a lower capacity. In addition, some of the listed capacity is used for formatting

and other functions, and thus will not be available for data storage. Seagate reserves the right to change, without notice, product offerings or specifications. Seagate

reserves the right to change, without notice, product offerings or specifications. DS1656.5-0909US

[jgs001]

it's to do with the size on the box using standard decimal (1000 to the kilo) and the way computers calculate (1024 to the kilo), therefore making the number on the box (1000) look bigger than the reality.

[beamish]

Ummm,One would have thought they'd be an internationally agreed stnd ! .....and avoid confusion

Cheers !

[themos]

As others have pointed out, the confusion is over the meaning of the G in GB. Some think it should be 1000*1000*1000 and some think it should be 1024*1024*1024.

Your manufacturer uses the former so it's 320,000,000,000 bytes.

The disk info program uses the latter so sees 298*1024*1024*1024 bytes.

[themos]

In that little computer over there I get

themos@hector-xt6-2:~> df -h /work
Filesystem            Size  Used Avail Use% Mounted on
19@ptl1:/lustrefs      84T   21T   59T  26% /work


themos@hector-xt6-2:~> df -H /work
Filesystem             Size   Used  Avail Use% Mounted on
19@ptl1:/lustrefs       92T    23T    65T  26% /work

So, which is it 84 terabytes or 92 Terabytes?

[beamish]

[Euan]

Big show off

[themos]

I try to keep it to once a year.

[themos]

By the way, the difference will amount to a factor of 2 for drives of

1,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000 bytes

[PhoenixRising]

in other words, dont worry about it...

[Abernus]

Ummm,One would have thought they'd be an internationally agreed stnd ! .....and avoid confusion

Cheers !

Welcome to the world of IT where things don't confirm to standards!!!!!!

[Sparrow]

I agree that it's misleading and on a computer forum I visit regularly it is a regular query - understandably.

Liken it to buying a car - you buy what you think is a 2 litre sports car with 500bhp. You find it's actually only 1.8 litres with 450bhp. The manufacturer says -"are it's just the way we measure is different to everyone else":)

As Abernus said - "Welcome to the world of IT"

This reminds me of the famous General motors reply to Bill Gates:):-

At a recent computer expo (COMDEX), Bill Gates reportedly compared the computer industry with the auto industry and stated: "If GM had kept up with technology like the computer industry has, we would all be driving $25 cars that get 1,000 to the gallon."

In response to Bill's comments, General Motors issued a press release (From Mr. Welch himself): "If GM had developed technology like Microsoft, we would all be driving cars with the following characteristics:"

1. For no reason whatsoever, your car would crash twice a day.
   
2. Every time they repainted the lines on the road, you would have to buy a new car.
   
3. Occasionally your car would die on the freeway for no reason, and you would just accept this, restart and drive on.
   
4. Occasionally, executing a maneuver such as a left turn, would cause your car to shut down and refuse to restart, in which case you would have to reinstall the engine.
   
5. Only one person at a time could use the car, unless you bought "Car95" or "CarNT." But then you would have to buy more seats.
   
6. Macintosh would make a car that was powered by the sun, reliable, five times as fast, and twice as easy to drive, but would only run on five percent of the roads.
   
7. The oil, water temperature and alternator warning lights would be replaced by a single "general car fault" warning light.
   
8. New seats would force everyone to have the same size butt.
   
9. The airbag system would say "Are you sure?" before going off.
   
10. Occasionally for no reason whatsoever, your car would lock you out and refuse to let you in until you simultaneously lifted the door handle, turned the key and grab hold of the radio antenna.
    
11. GM would require all car buyers to also purchase a deluxe set of Ran McNally Road maps (now a GM subsidiary), even though they would immediately cause the car's performance to diminish by 50% or more. Moreover, GM would become a target for investigation by the Justice Department.
    
12. Every time GM introduced a new model, car buyers would have to learn how to drive all over again because none of the controls would operate in the same manner as the old car.
    
13. You'd press the "start" button to shut off the engine.
    

[PaulG]

in other words, dont worry about it...

LOL