harddrive reporting wrong size

  polish 20:55 15 May 2005
Locked

mt seagate barracuda 120 gb hdd is reporting back as 111gb running xp sp2 any ideas please

  bremner 21:04 15 May 2005

That is correct.

Manufactures use:

1GB as being 1000MB instead of 1024MB.

1MB as being 1000KB when it is 1024KB

and 1KB as 1000bytes when it is 1024 bytes.

Windows sees the size as correct - you have not lost anything

  Fingees 21:12 15 May 2005

It sounds about right. some is taken up by formatting, and also the way space is calculated.
For instance I run a 200 Gb drive ie, 200,000,000,000+ bytes, but this works out at 186 Gbytes.

Manufacturers like to express capacity in the most favourable way for them.
All the best.

  Buchan 35 21:55 15 May 2005

A message for bremner and Fingees. I understand where you`re coming from, but does this mean that the 40Gig in my other unit that Belarc says is 40.78Gig is a true figure? Belarc also says that the 40Gig in this computer is only 38.45Gig which is probably about right

  DieSse 22:34 15 May 2005

If you look at the drive proerties in WinXP - you will see both figures shown :-

120,000,000,000 (approx)

and

111Gb (approx)

All drive manufacturers quote capacity figures using the International standard expression of K = 1000

The use of K = 1024 is a historical accident on computers, all down to a side effect of binary notation.

  DieSse 22:39 15 May 2005

If you look at the drive properties in WinXP - you will see both figures shown :-

120,000,000,000 (approx)

and

111Gb (approx)

All drive manufacturers quote capacity figures using the International standard expression of K = 1000

The use of K = 1024 is a historical accident on computers, all down to a side effect of binary notation.

  Monument 08:18 16 May 2005

"The use of K = 1024 is a historical accident on computers".

Nothing accidental about it, computers work on base 2 so it has to be 1024 rather than 1000.

We are just more comfortable with base 10 ie decimal.

  Maverick81 09:52 16 May 2005

When manufacturers produce drives they count the number of bytes in much the same way as we count pounds and pence – using decimal (base 10) notation. Because of the way computers work, the operating system can only recognise and organise the drive in binary (base 2) notation. This means that instead of a kilobyte being 1000 bytes as it would in decimal notation, in binary notation it is actually 1,024 bytes (2^10 which is 2 to the power of 10). So every software kilobyte takes an extra 24 bytes compared to the manufacturer’s reference. When kilobytes are multiplied to megabytes, and megabytes multiplied to gigabytes, this difference is exponential; it becomes far more noticeable. So
a Kilobyte is equal to 1024 bytes,
a Megabyte is equal to 1024 Kilobytes (1024 x 1024 bytes) = 1048576 bytes
a Gigabyte is equal to 1024 Megabytes (1024 x 1024 x 1024 bytes) = 1073741824 bytes
For instance, an 8.4GB (gigabytes) drive may contain approximately 8,438,652,928 bytes. If you look at the way an operating system organises the storage space, you will see that it reports a capacity of 7.859GB; 8,438,652,928 bytes /1024 (kilobytes) /1024 (megabytes) /1024 (gigabytes). In this way, a 17.1GB drive “loses” 1.25GB, a 35GB drive “loses” 2.5GB, a 70GB drive “loses” 5GB. Hard drive manufacturers have always sold and marketed their drives with reference to the actual number of bytes available and not with reference to how the operating system makes use of these bytes and this measure is also adopted by the PC industry en masse when describing the capacity of a computer’s storage medium.

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