This is less of a question and more of a “confirm that I’m not being screwed” thread.
I recently picked up a cheap 80GB hard drive (I went cheap because nothing I’m putting on this drive is terribly important – I’m just trying to cut back on the CD burning shuffle).
OK, I know computers measure bytes as 1,024 (IIRC) but hard drive manufacturer marketers use 1,000, the effect being that the advertised price of the drive is larger than what Windows 98SE actually reports available for use. No biggie to me, I knew the drive would be reported at a smaller capacity.
I get the drive installed, and it shows up in Explorer as 72.7 GB, an 8.3 GB haircut from the advertised size. That seems a bit more of a drop than I was expecting. My back of the envelope guestimation was that the drive would report at 77 gigs or so.
So what gives? Is my math bad, am I using incorrect assumptions, or am I getting screwed?
72.7 sounds about right, as long as I’m doing my math correctly. There’s 1024 bytes in a Kbyte, 1025 Kbytes in a Mbyte, etc. That multiplies to 1,099,511,627,776 bytes in a Gbyte. Divide that into 80 billion, and you get about 72.
The file system/indexing scheme takes up a certain amount of space on the drive. You have to map from the name of the file to the actual location of the file on the disk’s platters. To complicate matters, a file may not be contiguous on the disk, so you have to record the links between the segments. So in short, you have to devote a certain amount of space on the disk to recording where you put things.
Think of it as a 500 page book with a 50 page index. You only get 450 pages of actual info.
There are at least three possible sources of overhead:
[ul]
[li]Invisible files that aren’t appearing in the GUI desktop view.[/li][li]Data structures for the file system, which represent the disk’s files and directories and keep track of which blocks are in use. Even if the drive is “empty”, these structures still exist.[/li][li]Data structures for the disk’s partition map.[/li][/ul]
Any utility that lets you partition and reformat disk drives would probably show the “true” size of your disk — the actual number of blocks. Unfortunately I’m not a Windows person, so I don’t know the names of such utilities for that platform. There might be one included with the OS. Otherwise, one of the Linux distributions might have one you could grab for free.
Why are they allowed to misrepresnt their product by claiming it has more data storage than it really has? If all computers use 1024 kilobytes to a mega byte, why can the manufacturers use use 1000? wouldn’t that be false advertising?
Are the automakers allowed to use Canadian Gallons (I think a canadian gallon is slightly larger than an american one) when they are calculating their mpg?
I seem to remember a thread here a few months ago that debated this very point.
I would say that the hard drive manufacturers are simply taking advantage of an ambiguity in the language, one that they didn’t even create. The somewhat sloppy practice of employing “kilo-” to mean 1024 (and “mega-” to mean 1024[sup]2[/sup], and so on) began years before hard drives were affordable to the general public.
Every harddrive advertisement I have seen include a disclaimer stating 1000 Megabytes = 1 Gigabyte, amount shown varies based on what your operating system is, ect. You have to read the fine print, but it isn’t false advertising.
This has been discussed several times and you can find a lot of different opinions in those threads. The fact is that hard disk capacity has pretty much always been used like this and that the only ones who get confused are the ones who know little or nothing about computers and refuse to read the disclaimer. There are technical reasons why computer memory uses 1 KB = 1024 but it is that standard which deviates and not the other way around. Hard disk capacity, data transmission speeds and other measurements use 1K = 1000, as is the standard. The salesman can argue that rather than getting too little disk you actually got too much memory.
You can find this info at hard drive manufacturer’s web sites, or a google search if you would have tried. Here is what Maxtor’s web site says about it:
Question: The hard drive capacity in Windows Explorer or FDISK reports less than indicated on the drive label.Different applications reporting hard drive capacity in Binary versus Decimal.
Answer:
Hard drive manufacturers market drives in terms of decimal (base 10) capacity. In decimal notation, one megabyte (MB) is equal to 1,000,000 bytes, and one Gigabyte (GB) is equal to 1,000,000,000 bytes.
Programs such as FDISK, system BIOS, and Windows use the binary (base 2) numbering system. In the binary numbering system, one megabyte is equal to 1,048,576 bytes, and one gigabyte is equal to 1,073,741,824 bytes.
Simply put, decimal and binary translates to the same amount of storage capacity. Lets say you wanted to measure the distance from point A to point B. The distance from A to B is one kilometer or .621 miles. It is the same distance, but it is reported differently due to the measurement.
