Disk space differences as reported in windows explorer?


B

Bill in Co.

OK. Maybe this post belongs in this group instead.

When your right click on a drive in windows explorer, and get these
different reported sizes, what is the story?

Example, for a 20 GB partition - rounded to 3 significant digits below:
(choose whichever I guess; the two listings below are seen next to each
other in windows explorer):

12. 4GB 11.5 GB used spaee (tot capacity adds up to
19.9 GB)
7.56 GB 7.04 GB free space (tot capacity adds up to
18.6 GB)
(tot = 19.9 GB) (tot = 18.5 GB)

and as yet a third variation reported in BING:

11.9 GB used,
7.22 GB free
(total = 19.1 GB)

Anyone have a good explanation for the differences? I assume part of it
might have to due with the defenition of the HD sizes, e.g.: 1 GB or 1.024
GB, for "1 GB size" - not sure?

or for a 40 GB example:

20.36 GB 18.9 GB used space
19.64 GB 18.2 GB free space
capacity:
40.00 GB 37.2 GB
 
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B

Bill Blanton

Bill in Co. said:
When your right click on a drive in windows explorer, and get these
different reported sizes, what is the story?

Example, for a 20 GB partition - rounded to 3 significant digits below:
(choose whichever I guess; the two listings below are seen next to each
other in windows explorer):

12. 4GB 11.5 GB used spaee (tot capacity adds up to
19.9 GB)
7.56 GB 7.04 GB free space (tot capacity adds up to
18.6 GB)
(tot = 19.9 GB) (tot = 18.5 GB)

and as yet a third variation reported in BING:

11.9 GB used,
7.22 GB free
(total = 19.1 GB)

Anyone have a good explanation for the differences? I assume part of it
might have to due with the defenition of the HD sizes, e.g.: 1 GB or 1.024
GB, for "1 GB size" - not sure?

Sorta,,, and your rounding of the bytes to GB shows why it's not the same
thing.

Take this last example;

or for a 40 GB example:

20.36 GB 18.9 GB used space

It wasn't 20.36GB was it? It was 20,36n,nnn,nnn bytes. So, divide that number
by 1024^3 (or 2^30) and you'd get roughly 18.9GB
19.64 GB 18.2 GB free space

Divide 19,64n,nnn,nnn by 1024^3, and you get roughly 18.2
capacity:
40.00 GB 37.2 GB

So, bytewise

+ 20,36n,nnn,nnn
+ 19,64n,nnn,nnn
= 40,nnn,nnn,nnn

but 40,nnn,nnn,nnn bytes is not 40GB (in binary terms).
 
B

Bill in Co.

Bill said:
Sorta,,, and your rounding of the bytes to GB shows why it's not the same
thing.


It wasn't 20.36GB was it? It was 20,36n,nnn,nnn bytes. So, divide that
number
by 1024^3 (or 2^30) and you'd get roughly 18.9GB


Divide 19,64n,nnn,nnn by 1024^3, and you get roughly 18.2


So, bytewise

+ 20,36n,nnn,nnn
+ 19,64n,nnn,nnn
= 40,nnn,nnn,nnn

but 40,nnn,nnn,nnn bytes is not 40GB (in binary terms).

Thanks Bill. I'll have to digest this a bit more. But there is still a
point of confusion for me here. Giga just means 10 to the 9th, so I used
that as shorthand, but maybe that is incorrect or misleading to do for
binary expressions? Well, let's see...

So if the disk capacity shows as 40,000,nnn,nnn bytes, it is not "correct"
to express it as 40 X 10^9 bytes, or 40 E +09 bytes? (even though that
is the actual "number"?)
 
E

Ed Covney

So if the disk capacity shows as 40,000,nnn,nnn bytes, it is not
"correct" to express it as 40 X 10^9 bytes, or 40 E +09 bytes? (even
though that is the actual "number"?)

Bill, do you understand that there is a difference between the metric
term "Kilo" in Math or science vs. the computer term "Kilo"?

Metric Arithmetic Computer
Kilo 1000 1024
Mega 1,000,000 1024K = 1M
Giga 1,000,000,000 1048576K = 1024M = 1G
Tera 1,000,000,000,000 1073741824K = 1048576M = 1024G = 1T

I have some 12 yr old grand kids here in Co. that understand this, what
grade and school do you go to?

Mr. C.
 
B

Bill in Co.

Ed said:
Bill, do you understand that there is a difference between the metric
term "Kilo" in Math or science vs. the computer term "Kilo"?

Metric Arithmetic Computer
Kilo 1000 1024
Mega 1,000,000 1024K = 1M
Giga 1,000,000,000 1048576K = 1024M = 1G
Tera 1,000,000,000,000 1073741824K = 1048576M = 1024G = 1T

I have some 12 yr old grand kids here in Co. that understand this, what
grade and school do you go to?

Mr. C.

Kindergarten (but I still get confused by it sometimes!). So the error is
saying that 1,000,000,000 computer bytes is 1 GB.

OK, so let's try it again. 1 KB of RAM means 1024 bytes of RAM, period,
and it does NOT mean 1000 bytes of RAM (of available address locations).

And 1 GB memory really means 1.024 billion bytes, NOT 1 billion bytes!
So it is correct to say it means 1.024 E+09 bytes, but not 1.0 E+09 bytes.

Gotta keep reminding myself....senility may be setting in.
 
B

Bill Blanton

Bill in Co. said:
Thanks Bill. I'll have to digest this a bit more. But there is still a point of confusion for me here. Giga just means 10 to
the 9th, so I used that as shorthand, but maybe that is incorrect or misleading to do for binary expressions? Well, let's see...

So if the disk capacity shows as 40,000,nnn,nnn bytes, it is not "correct" to express it as 40 X 10^9 bytes, or 40 E +09 bytes?
(even though that is the actual "number"?)

10^9. That's not in-correct. That's how HD manufacturers define their drives.
And kilobits/sec, kilowatts, et al are de3fined by powers of 10.

However, Windows (more correctly IMO) defines storage space in powers of 2.
40GB = 40 * 2^30 = 42,949,672,960. (and since it isn't a power of 10 you
can't just move the decimal point to get to the next quantifier)

Since computers are mostly binary (n^2) beasts, (CPU, memory)
it was common in the early days to define a kilo-byte as 1024 bytes, and
not 1000 bytes (and so was "close enough"). I think it may have taken off
from there.


There was/is a movement under way to insert an "i' to denote binary ^2
to avoid the confusion. I.e KiB, Mib, GiB, TiB. It was supported by the IEC and
IEEE, but I don't think it ever really took off.

Here, I found this. (see "quantifiers")
http://www.ccil.org/jargon/jargon_32.html#TAG1443
 
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B

Bill in Co.

Bill said:
10^9. That's not in-correct. That's how HD manufacturers define their
drives.

Yeah, unfortunately, unlike the rest of the computer stuff.
And kilobits/sec, kilowatts, et al are de3fined by powers of 10.

However, Windows (more correctly IMO) defines storage space in powers of
2.
40GB = 40 * 2^30 = 42,949,672,960. (and since it isn't a power of 10 you
can't just move the decimal point to get to the next quantifier)

But I could rewrite the number above as: 42.949672960 E+09, and it would be
correct. Or as: 42.949672960 X 10^9. But that's different than 40E
+09
Since computers are mostly binary (n^2) beasts, (CPU, memory)
it was common in the early days to define a kilo-byte as 1024 bytes, and
not 1000 bytes (and so was "close enough"). I think it may have taken off
from there.

I think so too, but sometimes it still confuses me. I hate the fact that
the HD manufacturers went the other way (inconsistent with the std computer
binary approach). And I believe this was *soley* done to inflate their
numbers as an advertising gimmick. So they could sell a 40 GB drive and
people thought they got 40 GB of actual storage, but they don't.
There was/is a movement under way to insert an "i' to denote binary ^2
to avoid the confusion. I.e KiB, Mib, GiB, TiB. It was supported by the
IEC
and IEEE, but I don't think it ever really took off.

Maybe that would have helped.
There are some things the IEEE did that certainly did not help, I feel.
(e.g:: I dislike conductance being expressed in the new units of Siemens,
much preferring the good ole "mhos"; and changing to "mA" (e.g) for
milliamps in lieu of mA (this, to "honor the guys"), and using "Hz" in lieu
of the more logical "cps" (for anybody old enough to remember :)

Thanks again.
 

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