What's the TRUE capacity?

Contemplating going to the Applestore this morning to buy an iPod classic. The decision on size rests largely on the TRUE capacity. I am replacing my 60Gb 5G which my music collection has outgrown. The TRUE capacity of this was 55.7Gb. I now have 76Gb of music, photos and videos - will this fit on an 80Gb?

I know that this is an old trick of the HD manufacturer but in my opinion 80Gb should have a capacity of 80Gb and the 160Gb should hold 160Gb. If I bought a petrol can that claims to hold 5 Gallons and took it to the filling station only to end up with petrol all over my leg because the TRUE capacity was 4.6 Gallons I would be severely annoyed.

iMac G5 17", iPod 5G 60GB, iPod nano 4Gb second gen, Mac OS X (10.4.10)

Posted on Sep 9, 2007 1:16 AM

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14 replies

Sep 9, 2007 2:36 AM in response to RDH

This will give you an idea:
1 KB = 1024 bytes
1 MB = 1024 KB = 1048576 bytes
1GB = 1024 MB = 1048576 KB = 1073741824 bytes
So take 4.7 billion bytes, and start dividing by 1024:
4,700,000,000 bytes = 4,589,843 KB = 4,482 MB = 4.37 GB


Hard drive manufacturers define 1 gigabyte as exactly 1,000,000,000 bytes. By their definition, a 45BG hard drive is exactly 45,000,000,000 bytes. The true definition of 1 gigabyte is actually 1,073,741,824 bytes:
* 1024 bytes = 1 kilobyte
* 1024 kilobytes = 1 megabyte
* 1024 megabytes = 1 gigabyte
To obtain the true size in gigabytes of a 45BG hard drive you must divide the manufacturer's size in bytes by the number of bytes in a gigabyte:
45,000,000,000/1,073,741,824 = 41.9
As such, the actual reported size in gigabytes will always be smaller than the manufacturer's advertised size.

Sep 9, 2007 7:13 AM in response to koosipet

Thanks for the reply. My point though is why not used the same system to measure the drive as one uses to measure the data to fit on it? I know there's small print but surely it would be better to be honest?

BTW I bought a 160Gb iPod and can report that it holds 148Gb.Why not call it a 150Gb? Closer to the mark innit!?

Sep 9, 2007 7:43 AM in response to RDH

My 160 GB showed 148.65 GB free after a restore on my Mac (HFS+ formatting). I'm guessing an 80 GB will lose 5-6 GB after formatting, but hopefully someone with an 80 GB model will respond with an exact figure.

I think you're going to need to spring for a 160 GB if you want to hold your existing material and have a bit of breathing room.

Also, the actual formatted capacity may differ depending on the number of bad blocks on a drive and whether it is formatted HFS+ or FAT32.

Sep 9, 2007 8:50 AM in response to kasplat

For Gigabyte storage drives, the actual storage is always 0.93 times the stated storage. And formatting has nothing to do with it. Formatting takes up very little space, not gigabytes worth.
"80GB" = 74.4 Gigs
"160GB" = 148.8 Gigs
Then a little room will be taken up by the iPod's loaded stuff but this should be on the order of maybe a few hundred megabytes.
Patrick

Sep 9, 2007 5:18 PM in response to RDH

My point though is why not used the same system to measure the drive as one uses to measure the data to fit on it? I know there's small print but surely it would be better to be honest?


Back in the 1970's and early 1980's, some computer companies would use the "honest" number when advertising the amount of memory in their computers. But other computer companies would use the "less honest" number. Computer buyers would see two computers for sale at the same price but one of them would list a higher amount of memory. So, of course, the computers from the less honest companies would sell better even though the actual amount of memory was the same. This left the honest companies little choice but to adopt the less honest numbers.

Once hard drives started to appear, the practice was extended to them. People did not notice this at first because the difference between the honest and less honest numbers was not large. But as hard drive sizes increased, the difference became greater.

Sep 9, 2007 6:21 PM in response to RDH

Got my 160gb today or should i say 148? I understand a few gigs of ipod OS but seriously. 12GB?!?! I completely understand the 160gb is the raw HD but when over 10gb of it isn't there for storage how can they honestly sell it as 160? Am I crazy? I love Apple products etc like most of us on here however this is dumb. I'd complain if I knew who to contact.

Sep 9, 2007 6:38 PM in response to jrcsh6

The issue is more to do with the drive manufacturers (Western Digital, Maxtor, Seagate, etc.) more so than Apple. Take a look at the hard drive in your computer. It is exactly the same situation. The "80GB" or "160GB" or whatever size drive you got with your iMac is actually only 93% the size you thought your were getting. So if you iMac came with a "160GB" drive, then the actual storage space is 148GB.
Drive manufactures lie, errr, I mean creatively state that the size of their drives use 1000 as a kilobyte. A real kilobyte is actually 1024.
1000x1000x1000 = 1 creative "Gigabyte". But the drive actually is 1024x1024x1024 = 1073741824 bytes (1 real gigabyte).
( 1,000,000,000 creative GB / 1,073,741,824 real GB) = 0.9313
Patrick

Sep 15, 2007 9:00 AM in response to RDH

RDH wrote:
Thanks for the reply. My point though is why not used the same system to measure the drive as one uses to measure the data to fit on it? I know there's small print but surely it would be better to be honest?

BTW I bought a 160Gb iPod and can report that it holds 148Gb.Why not call it a 150Gb? Closer to the mark innit!?


Think about the Games, the Software, the RAM support needed. Surely, the more the memory as advertised, the less formatted capacity you will have.

Sep 15, 2007 11:15 AM in response to RDH

I don't want to prolong this discussion, which occurs all over the forums when reference to hard drive sizes is made. As stated in the footnotes on the tech specs page for all current ipods "1GB = 1 billion bytes; actual formatted capacity less." Therefore, Apple is using this definition of GB, which is perfectly OK according to Wikipedia (see entry for Gigabyte), and is the general industry practice. For example, here is a link to a large flash memory manufacturer's explanation: <http://www.sandisk.com/Assets/Categories/Products/sd_capacitydisclaimer.pdf>.

bd

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What's the TRUE capacity?

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