Hard disk size - quoted & actual

[chrisv]

Hi all,

This is something I've often wondered about but never tried to find out
- why is it that when you buy a 400GB drive, hook it up to your
motherboard, you only get say 370GB? This is before it's been formatted
or anything.

Hi all, This is something I've often wondered about but never tried to
find out - why is it that cretins are always coming along asking
questions like this, in the apparent belief that they are the first
person ever to post the question on USENET? Do they think they're
that unique? Have they never heard of doing a google search?

 

[Grunff]

Hi all, This is something I've often wondered about but never tried to
find out - why is it that cretins are always coming along asking
questions like this, in the apparent belief that they are the first
person ever to post the question on USENET? Do they think they're
that unique? Have they never heard of doing a google search?

While I'd normally ignore idiotic responses such as this, since this is
my first post to the group, I'll respond.

I did google, extensively, this group (including its FAQ), other groups,
and the web. I found lots of questions, but no answers that satisfied my
curiosity.

I found lots of answers referring to file system overhead etc., as
posted by several people in this thread - but my question is about
non-formatted drives.

I now understand the reason, and also understand the mistake I was
making (1024 not 1024^3), thanks to some very helpful answers.

There will always be some level of repetition on Usenet - learn to live
with it.

 

[Nick]

Well, the basis of the measurement of a bit (Binary digIT) is of course
binary. A byte = 8 bits,

http://en.wikipedia.org/wiki/Byte

The word "byte" has several meanings, all closely related:

1. A contiguous sequence of a fixed number of bits. On modern
computers, an eight-bit byte or octet is by far the most common. This
was not always the case. Certain older models have used six-, seven-,
or nine-bit bytes - for instance on the 36-bit architecture of the
PDP-10. Another example of a non eight-bit sequence is the 12-bit slab
of the NCR-315. A byte is always atomic on the system, meaning that it
is the smallest addressable unit. An eight-bit byte can hold 256
possible values (28 = 256) -- enough to store an unsigned integer
ranging from 0 to 255, a signed integer from -128 to 127, or a
character of a seven-bit (such as ASCII) or eight-bit character
encoding.


Nick

 

[Rod Speed]

Well that was my comment.
Yep.

Then you said it was wrong.

Nope, I said the next bit is wrong. Here it is again

-----------------------------------------------------------------------------------

I'm sorry if my first post was misleading,

Much of it was just plain wrong.

but I believe you are misinterpreting it from my intentions.
Nope.

I never mentioned memory or storage.

I rubbed YOUR nose in the FACT that while memory does have
an intrinsically binary ORGANISATION, hard drives do not.

So while the binary 2^x form makes sense
with memory, it doesnt with hard drives.

I am talking about the origin of the terms bit and byte.

Pity that was completely irrelevant to what was being discussed,
the use of the 2^x or 10^x forms for stating the amount of whatever.

Those origins predate the use of the magnetic, non-volatile storage we use
today.

Also completely irrelevant.

 

[Rod Speed]

http://en.wikipedia.org/wiki/Byte

The word "byte" has several meanings, all closely related:

1. A contiguous sequence of a fixed number of bits. On modern
computers, an eight-bit byte or octet is by far the most common.
This was not always the case. Certain older models have used
six-, seven-, or nine-bit bytes - for instance on the 36-bit architecture
of the PDP-10. Another example of a non eight-bit sequence is
the 12-bit slab of the NCR-315. A byte is always atomic on
the system, meaning that it is the smallest addressable unit.

Then you have a problem when using bytes with a PDP-10

The term used with that era was normally a word, not a byte.

 

[Rod Speed]

Grunff wrote:

Hi all, This is something I've often wondered about but never tried to
find out - why is it that cretins are always coming along asking
questions like this, in the apparent belief that they are the first
person ever to post the question on USENET? Do they think they're
that unique? Have they never heard of doing a google search?

Its one of those things that arent that easy to use google
for if you arent very good at google searches, as most
of those who ask that sort of question arent.

We could also ask why you didnt answer
your own question using a google search too.

The answer is rather obvious, you've got nothing
better to do than ask stupid questions like that.

 

[Arno Wagner]

Hi all,

This is something I've often wondered about but never tried to find out
- why is it that when you buy a 400GB drive, hook it up to your
motherboard, you only get say 370GB? This is before it's been formatted
or anything.

HDD manufactueres sell you n units of storage. The legal units are
prefixed by SI prefixes, i.e. multiples of 1000. Ram is sold in
number of address lines, which results in powers of two. Thes units
are illegal, but since you cannot have a 19MB chip or the like, these
are not considerd units of measurement but instead something like
size-classes, like a 2 family house or a 4 person car. However since
HDDs can have almost any size, the manufacturers are required by
law almost anywhere to use the correct SI prefixes.

I don't normally mind/notice the loss, but I've just built a RAID array,
and it was a bit of a shock that all I ended up with was 1.8TB instead
of 2.0TB.

You have 2TB. You also habe 1.8TiB. Ti is not a legal SI prefix,
but a IEC standard exists. Look here:

http://physics.nist.gov/cuu/Units/binary.html

If somebody shows 2TB as 1.8TB they are in violation of the laws
on units and measurements in allmost all countries. Not that
anybody seems to care.

Arno

 

[Kevin Buffardi]

1. A contiguous sequence of a fixed number of bits. On modern
computers, an eight-bit byte or octet is by far the most common. This
was not always the case. Certain older models have used six-, seven-,
or nine-bit bytes - for instance on the 36-bit architecture of the
PDP-10.

While it's true that a byte doesn't always have to be 8-bits, it's
notable that these cases are rare. Even as the beloved Wikipedia says,
"eight-bit byte [...] is by far the most common." But, no excuses for
me... I should have said, "A byte *typically* = 8 bits."

Another thing to point out that is even more relavent to the thread:
http://en.wikipedia.org/wiki/Kilobyte

As shown here, yes Rod is correct that 1KB = 1000 bytes in International
System of Units standards. HOWEVER, "1,024 [...] is used to express
memory capacity *and by most software to express storage capacity.*
This was obviously the case for Grunff's mobo report of the hard drive
capacity.

//Kevin

 

[Rod Speed]

Another thing to point out that is even more relavent to the thread:
http://en.wikipedia.org/wiki/Kilobyte

Doesnt make it gospel.

As shown here, yes Rod is correct that 1KB = 1000 bytes in International
System of Units standards. HOWEVER, "1,024 [...] is used to express memory
capacity *and by most software to express storage capacity.* This was
obviously the case for Grunff's mobo report of the hard drive capacity.

Duh.

Separate issue entirely to the errors in YOUR original.

 

[Folkert Rienstra]

1. A contiguous sequence of a fixed number of bits. On modern
computers, an eight-bit byte or octet is by far the most common. This
was not always the case. Certain older models have used six-, seven-,
or nine-bit bytes - for instance on the 36-bit architecture of the
PDP-10.

While it's true that a byte doesn't always have to be 8-bits, it's
notable that these cases are rare. Even as the beloved Wikipedia says,
"eight-bit byte [...] is by far the most common." But, no excuses for
me... I should have said, "A byte *typically* = 8 bits."

Another thing to point out that is even more relavent to the thread:
http://en.wikipedia.org/wiki/Kilobyte

As shown here, yes Rod is correct that 1KB = 1000 bytes in International
System of Units standards. HOWEVER, "1,024 [...] is used to express
memory capacity *and by most software to express storage capacity.*

This was

What was.

 

[Kevin Buffardi]

What was.

This:

"1,024 [...] is used to express
memory capacity *and by most software to express storage capacity.*

//Kevin