The disc allocation information does use a bit of it, however, it does not use as much as you are saying. If you look at the spec sheet from the manufacturer of the drive, it will say that they are using the 1,000 system and not 1024. This is completely a marketing ploy that worked a lot better when people were using 1 to 5 gig drives, because then you could say the small amount left was being used by the access tables, however, with current 750 gig drives and terabyte drives, it just doesn’t make sense and isn’t true. If you call the company and complain enough, they will admit it, but not fix anything.

I even bought another 500 GB external hard drive last week.
I cleared everything I could think of from my various folders
and files.
it freed up approx 7 GB”s.

I unplugged the external hard drive and checked my drive space,
approx 7 GB free space.

The hard drive remains unplugged.
I add no new programs.
I use the computer very little, only checking e-mails.

Two days later I get another low disk space warning.
24 mega bites left.
What in the world is up with all of this???

AFAIK, the thing is that a 80GB HD has 80Gb of raw space. You can actually store 80*1024^3 bytes, but that is an obscene amount of data and you need to organize it some way. That is when the Filesystem comes in and takes a part of it for the Allocation Table.

The more complex your filesystem is, in general, the more space it takes. Using a fairly complex FS with journaling, user permissions and three levels of users (like Unix systems like Mac do) takes more space than using the old FAT 32 system.

Moreover, there is the block size. Data is stored in small indivisible sequencial blocks and its size may vary.

Because they are indivisible and sequencial, part of them is wasted for every file, so you have an average waste of (number of files)*(block size)/2. To prevent this you can reduce the block size, but keep in mind that this will affect performace and also may reflect on a bigger allocation table, because there are more blocks to index.

Ha ha!, Yeah, maybe!

Wow, that’s a pretty large index file!

I’ve been wondering where it has been going, and I found the culprit…Google Desktop.

The index file is something around 5GB for my machine, and constantly growing I assume.

Crikey!

I mean, people will look at how large their computer syas the disk is, compare to the ad, and be dissatisfied.

Carl,

You cheeky, you…
Actually, I think the ozone layer is in fairly good shape over Sweden, thank you very much.

The term you’re looking for is Gibibyte which is where the powers of 1024 come into play.

Just FYI
Cheers.

This different comes from the binary system. Computers store bits. If you want to know how many elements you can name with any given number of bits you just power two to the number of bits and you get their span:

2^1 = 2 => you can name two addresses with 1 bit (0,1)
2^2 = 4 => you can name 4 addresses (00,01,10,11)
2^3 = 8 => 8 addresses (000,001,010,100,101,110,011,111)
…
2^10 = 1024, so people didn’t want to simply ignore those extra 24 places just to make it easier for common folk to read “kilobytes”.

Thus was born the different of the prefixes Kilo- Giga- Tera- Peta- when it comes to bytes.

( Thought someone might want to know the story behind the 1024… )

And I think apple has a disclaimer about this (bottom of the apple.com shop page), in small, grey text, as if they didn’t want yo to see it ;).

This is same as iPod’s. For example iPod nano 4GB is actually 3.7GB. You are damn right about advertising, they should advertise what they are giving us.