Hard Drive 'Available Space' Question

[Lionheart]

Hey guys,


I notice that when I install or format a drive (HD), that it never shows the full amount on the HD. For instance, a TB HD drive shows 931 Gigs available. A 320 Gig HD shows 298 Gigs available.


Whats up with that??



Bill

[Willy]

They all do that. Not sure of the exact reason.

[hey_moe]

Do you have the retore feature selected and what are you using to format the drives with...and don't say a tooth brush.

[IVANOW]

Mine did the same.

[Wiens]

Picked this off the web:


Hard drives are sold and marketed using decimal gigabytes. That is, a “GB” consists of 1,000,000,000 bytes.
However, computers interpret gigabytes in binary. To a computer, 1 GB = 2^30 bytes, or 1,073,741,824 bytes.
The ratio of “actual” to “marketed” file size is the ratio of these two interpretations, or roughly 0.9313225.
Therefore an X-sized (marketed) drive actually has 0.9313225*X of space usable to a computer.
Ex:
------------------------------------------------------
60GB*0.9313225 = 55.88GB
40GB*0.9313225 =37.25 GB
30GB*0.9313225 = 27.94GB
20GB*0.9313225 = 18.6 GB
15GB*0.9313225 = 13.97GB
10GB*0.9313225 = 9.31GB
6GB*0.9313225 = 5.59GB
5GB*0.9313225 = 4.67GB
4GB*0.9313225 = 3.73GB
1GB*0.9313225 = 0.93GB
512MB*0.9313225 = 476.84MB

This was for a question about iPod hard drives but I believe it applies somewhat here....

Kevin

[rayrey10]

I believe it has to with the binary system. Like how a kilobyte is not 1,000 byte but actually 1,024. A "meg" is actually 1,048,576 bytes not 1,000,000. So when you round it off some gets "lost".

Check this article out: http://www.dewassoc.com/kbase/hard_drives/hard_drive_size_barriers.htm

This one also explains it: http://www.allensmith.net/Storage/HDDlimit/Address.htm

Surprised I still remember that from college :typing:

[Lionheart]

Picked this off the web:


Hard drives are sold and marketed using decimal gigabytes. That is, a “GB” consists of 1,000,000,000 bytes.
However, computers interpret gigabytes in binary. To a computer, 1 GB = 2^30 bytes, or 1,073,741,824 bytes.
The ratio of “actual” to “marketed” file size is the ratio of these two interpretations, or roughly 0.9313225.
Therefore an X-sized (marketed) drive actually has 0.9313225*X of space usable to a computer.
Ex:
------------------------------------------------------
60GB*0.9313225 = 55.88GB
40GB*0.9313225 =37.25 GB
30GB*0.9313225 = 27.94GB
20GB*0.9313225 = 18.6 GB
15GB*0.9313225 = 13.97GB
10GB*0.9313225 = 9.31GB
6GB*0.9313225 = 5.59GB
5GB*0.9313225 = 4.67GB
4GB*0.9313225 = 3.73GB
1GB*0.9313225 = 0.93GB
512MB*0.9313225 = 476.84MB

This was for a question about iPod hard drives but I believe it applies somewhat here....

Kevin



Oh man....! Rip!!!

lol..

arrghh.


So a One Terrabyte has only 931 or so Gigs useful data area instead of 1TB...




Oh well.



:banghead:



Bill

[stiz]

yup "only" 931 gigs! :d

[Gnoopey]

Oh man....! Rip!!!

lol..

arrghh.

So a One Terrabyte has only 931 or so Gigs useful data area instead of 1TB...

snipped ....

.... unfortunately, that's NOT the whole 'story' - LOL - it's even 'worse' :wavey:

We all are 'victims' of the JEDEC <=> SI (IEC) 'war' :monkies:

In this 'bean counters times' - let's do some more byte counting ...

1 TB (terabyte) = 10^12 bytes = 1000 GB

2^40 bytes = 1 TiB (tebibyte) = 1024 GiB

'Problem' is - current MS operating systems (and others) use binary definitions for a GB (or are / were too 'lazy' to write GiB instead of GB) while most storage manufacturers use the SI prefix system.

Please don't get confused, that there are still a lot of sites around, that make a difference between a "binary" and/or a "decimal terabyte" - NONsense IMNSHO!

While the 'Wiens table' is quite accurate for GB 'conversion - it's 'wrong' for the MB conversion. (see over here ==> http://www.brettbits.com/Text/MissingHardDriveSpace/ )



Read:

1 TB ~ 0.9095 TiB
1 GB ~ 0.9313 GiB
1 MB ~ 0.9536 MiB
References:

SI prefixes:

=> http://physics.nist.gov/cuu/Units/prefixes.html
=> http://en.wikipedia.org/wiki/SI_prefix

SI binary multiples / binary prefixes:

=> http://physics.nist.gov/cuu/Units/binary.html
=> http://en.wikipedia.org/wiki/Binary_prefix

JEDEC memory standards => http://en.wikipedia.org/wiki/JEDEC_memory_standards
On the other hand, if you continue to use 'terrabytes', 'gigs' and 'megs', you're quite 'safe' ;)

'Sorry' Bill but I just couldn't resist - LOL

[deKoven]

Dunno zackly what the fuss is about. Drives have, from the very beginning, had this discrepancy. It's also true of your, excuse the expression, floppys (I know that the newer users among us have no clue what that is.)

:gossip:

[Snuffy]

A certain amount of space is taken by the install of the drive to tell it what it is and how to function. Its also space reserved for the file tables. :)

[srgalahad]

Floppy drive: (n) a 1937 Citroen painted by Salvador Dali

or: a computer disk(ette) in a variety of formats. 8" and 5.25" were a flexible (floppy) form replaced by a 3.5" rigid disk while the "floppy" name stuck.

http://upload.wikimedia.org/wikipedia/commons/thumb/8/88/Floppy_Disk_Drive_8_inch.jpg/728px-Floppy_Disk_Drive_8_inch.jpg


"The DataTrak 8 stores 1.6M bytes of unformatted data and 1.2M bytes of IBM-formatted data. Track-to-track access time is three msecs, average access time is 91 msecs, and settling time is 15 msecs. The drive's data transfer rate is 500K bits per second. Standard options include file protection, programmable door lock, and activity light. The drive is compatible with all existing drives, including IBM.

The DataTrack 8 is immediately available and is priced at $755 in OEM quantities of 1-24."

[Snuffy]

I still have 4 5.25 floppy drives and at least 8 boxes for books from U-Haul with 5.25 software in them. I suppose one day I need to hook the 5.25 to my current machine and burn the 5.25s to a dvd.

:help: