[hondo]

I just purchased a MB Pro with a 320 GB 7200 hard drive. The system profiler says its only 300GB. Am I missing something or does Apple owe me 20 GB?

Hitachi HTS723232L9SA62:

Capacity: 298.09 GB
Model: Hitachi HTS723232L9SA62
Revision: FC4AC40B
Serial Number:
Native Command Queuing: Yes
Queue Depth: 32
Removable Media: No
Detachable Drive: No
BSD Name: disk0
Mac OS 9 Drivers: No
Partition Map Type: GPT (GUID Partition Table)
S.M.A.R.T. status: Verified
Volumes:
Macintosh HD:
Capacity: 297.77 GB
Available: 243 GB
Writable: Yes
File System: Journaled HFS+
BSD Name: disk0s2
Mount Point: /

[iREZ]

you can't be serious?

google "actual hard drive space" and therein your answer shall lie.

basically... advertised ≠ actual (windows, linux or mac)

[hondo]

I realized that you don't actually get the full-advertised size but didn't take into account the fact that, as the drives get larger, I would see a larger deficit. Brain hiccup (getting old I guess) and I haven't bought a computer for a while. Sorry to have wasted your time. I won't make that mistake again.

[Maflynn]

Don't mind iRez, evidently he's forgotten that not everyone knows every little detail like he does and people come to MacNN to bask in the glow of his immense knowledge

298gig is normal because how the computer calculates a gigabyte and how marketing folks lie, err umm advertise.

[hondo]

I appreciate it. As you can see, I have been registered for some time and I do try to come here as much as I can to learn from the questions that are posted. I have had questions from time to time and I try to figure them out myself first. When I have asked, I have found that the folks on here are friendly and helpful.

No offense taken.

Hondo

[marclapierre13]

You never get the full amount of HD space. Example, 320gb will never be 320, itll be less. Like the other poster said, try google for the exact reason

[mduell]

320GB is 298GiB. That the OS reports the latter figure as GB, ignoring scientific and standards conventions, is annoying.

[tooki]

Ultimately, it's around a 7% loss. Stupid, indeed.

[Powerbook]

(cleanup)

[shawmanus]

it is actually 320 * 10^9 bytes. If u divide that thrice by 1024 you get 298.023GB. I wish marketing is more ethical as it is not 320GByte but 320*10^9 bytes.

[bearcatrp]

Make a few partitions to recoop some of it.

[Simon]

The partitioning won't change anything regarding the GB vs. GiB issue. There will always be a (1.024/)^3 =~ 1.073 scaling factor. For the customers that means they'll be getting 7% less than they expect. And as we move to TB disks you can add another power to that scaling increasing the difference to around 10%.

[Powerbook]

(cleanup)

[irockdabari]

I thought the rest of your files were scaled accordingly, thus actually giving you the "relative" hard disk space that you purchased.

[0157988944]

What I don't get is why they continue to advertise drives as 320 GB, etc when they know that not one computer will actually display it as such. What's the point, other than angry customers? It's not like the "actual formatted capacity" varies from machine to machine so they put 320 as an approximation. They know it'll show up as ~ 300 GB, so why not advertise it as such.

[ghporter]

While we who dabble or specialize in such things understand that "gigabytes" (or "kilobytes" for that matter) are actually a binary value rather than a scientific notation value, "Joe Consumer" generally doesn't have a clue. Expressing things in "billions of bytes" as opposed to "1.024 X 1 billion" bytes is indeed dumbing down the information, but since the bulk of consumers don't know crap about it anyway, at least drive makers are (for the last several years, anyway) reflecting which value they're reporting on the box, rather than just letting people believe what they believe.

[tooki]

Originally Posted by irockdabari 

I thought the rest of your files were scaled accordingly, thus actually giving you the "relative" hard disk space that you purchased.

In a nutshell, not any more.

On really, really old filesystems (like the old HFS, aka Mac OS Standard), the number of blocks on a partition (the smallest unit of storage; a file consumes multiples of these) was fixed. Consequently, on a bigger drive, the blocks were bigger, so the waste from blocks that weren't full would grow.

[example to follow uses made up numbers]
For example, let's say that we're using a format where a 500MB drive would have had a block size of 4KB, where a 1GB drive would have had an 8KB block size. Then you write a 2KB file. Since files must use whole blocks, then that 2KB file will use a whole block -- 4KB or 8KB, respectively. That results in waste (called "slack") of 2KB or 6KB, respectively. This is also the case for larger files. Let's say you're writing a 51KB file. On the 500MB drive, you'd completely fill 12 blocks and partially fill one more, for 13 blocks used, wasting 1KB of the last block. On the 1GB drive, you'd be using 7 blocks, but would be wasting 5KB of a block. Now imagine a 20GB hard drive, which would have 160KB blocks, causing HUGE amounts of slack.

If you've ever wondered what the difference is in the Finder's Get Info window, where it says, for example, "48KB on disk (48,545 bytes)", the first number is the file size plus its slack, while the second number is the exact size of the file without slack.

That's why partitioning into small partitions could help reduce slack.

But modern filesystems (like HFS+, aka Mac OS Extended) have fixed block sizes (typically 4KB), and have essentially limitless numbers of blocks, so there is NO efficiency gain from partitioning.

Think of the hard drive as a cupboard, and the blocks are little jars. On old filesystems, the number of jars was fixed, so a bigger cupboard held larger jars. On new filesystems, the jars are always small, but the number of jars is flexible. Now as you fill jars with, say, different kinds of pickles, you can fill more than one jar with the same pickles, but you can't mix two kinds of pickles in the same jar. So if you have one and a half jars' worth of a kind of pickles, you must waste 1/2 jar of space in the cupboard. Bigger jars can waste more space, as you can imagine.

[mduell]

Originally Posted by adamfishercox 

What I don't get is why they continue to advertise drives as 320 GB, etc when they know that not one computer will actually display it as such. What's the point, other than angry customers? It's not like the "actual formatted capacity" varies from machine to machine so they put 320 as an approximation. They know it'll show up as ~ 300 GB, so why not advertise it as such.

Who's going to buy the 300GiB drive when the 320GB drive right next to it is the same price?

The real solution is for software to start using the proper/official SI units for base-2 prefixes.

[0157988944]

Originally Posted by mduell 

Who's going to buy the 300GiB drive when the 320GB drive right next to it is the same price?

The real solution is for software to start using the proper/official SI units for base-2 prefixes.

Exactly. Everyone would have to advertise it as what it is.

[Simon]

To clear up the mess, a manufacturer could start adding capacity to their drives so the drive they sell as "320 GB" actually offers 320 GB. But adding those extra 7% capacity costs money. That's a disadvantage compared to all the competitors selling 299 GB HDDs under the same 320 GB label. And since all HDD manufacturers know that, they just keep everything as it is.

The only thing to do about it: educate yourself. Know what it means beforehand when a HDD manufacturer sells as a drive as containing so and so many GBs. And of course software should take this into account. If you're going to inform people about the details, then do it right.

[Maflynn]

The one thing that keeps bugging me on this issue is the fact that when computer companies were selling CRTs and they advertised a 15" crt, you didn't really get that in actual viewing area. They were sued, made some lawyers very rich and changed how they marketed the monitors.

Why hasn't this happened with the hard drives? I paid X dollars for a 320 gig drive but I'm only getting < 300 gig - this seems ripe for a lawsuit but drive manufacturers have been doing this for years.

[Simon]

I thought there actually was such a lawsuit. But IIRC the manufacturers won. If you look closely there's usually an asterisk somewhere. If you then get out a micrscope you'll see something like this

Originally Posted by Apple

1GB=1 billion bytes; actual formatted capacity less.

[hbone]

9GB for OS 10.5 + all those updates

Same with itunes 200MB and iLife updates

Security updates

blah blah blah