G5 Hard Drive Question (noobish) at DVinfo.net

Evan Estay · February 24th, 2005, 04:54 PM

I recently bought a Maxtor 300gb SATA HD. After installing and partioning (just 1) the drive, it only shows up as having 279 gigs free.

is this some kind of bug or is this normal? I am running the latest OSX.

just checking, any help appreciated

thx =]

Rhett Allen · February 24th, 2005, 05:12 PM

It's normal.
Hard drive manufacturers rate capacity using the formula 1000MB=1GB when in reality if you actually format the drive it is 1024MB=1GB. You will lose a little less than 10% capacity when you format the drive because of this and the drives directory structure. If you left it unformatted it would be 300Gig, but it wouldn't do you any good that way.

Boyd Ostroff · February 24th, 2005, 05:17 PM

Actually this is just the age-old confusion about the definition of a kilobyte/megabyte/gigabyte. In reality, a kilobyte is 1024 bytes (not 1,000) and a megabyte is 1,048,576 bytes (not 1,000,000) and a gigabyte is 1,073,741,824 bytes.

Divide 300 by 1.074 and you get 279.33, which is what the Finder is telling you. This has been a source of confusion for everybody since the days of multi-megabyte disks! Disk Utility will tell you the full story. For example, if I look at a 100GB drive on my own system it reports: 93.16 GB (100,030,242,816 Bytes).

Naturally, drive manufacturers use the math which makes their drives appear larger (eg: number of bytes and not the true definition of a Gigabyte).

Boyd Ostroff · February 24th, 2005, 05:19 PM

Rhett: looks like we posted at the same time... Look at my math, that's all that's happening. I think the space used for directories on a 300 GB drive is trivial, certainly not 21 GB!

Rhett Allen · February 24th, 2005, 08:42 PM

Nice math there Boyd! I knew there was a divisor in there somewhere. I just always rounded it to 10% because I'm math-lazy (at least about some things).
I don't know why they don't just make the drives OVER-sized so it comes out to 300Gig (or whatever they're claiming) after it's formatted, otherwise it's kind of misleading advertising.

Greg Boston · February 25th, 2005, 07:47 AM

I am looking at the same drive and am glad that it works ok. It has a 16mb cache as well. Evan, can you give some info about how well it is working in your system?

Thanks,

-gb-

February 24th, 2005, 04:54 PM	#1
Evan Estay Regular Crew Join Date: Nov 2004 Location: Hollywood Posts: 28	G5 Hard Drive Question (noobish) I recently bought a Maxtor 300gb SATA HD. After installing and partioning (just 1) the drive, it only shows up as having 279 gigs free. is this some kind of bug or is this normal? I am running the latest OSX. just checking, any help appreciated thx =]

February 24th, 2005, 05:12 PM	#2
Rhett Allen Major Player Join Date: Mar 2002 Location: Plano, TX Posts: 607	It's normal. Hard drive manufacturers rate capacity using the formula 1000MB=1GB when in reality if you actually format the drive it is 1024MB=1GB. You will lose a little less than 10% capacity when you format the drive because of this and the drives directory structure. If you left it unformatted it would be 300Gig, but it wouldn't do you any good that way.

February 24th, 2005, 05:17 PM	#3
Boyd Ostroff Wrangler Join Date: Dec 2002 Location: Mays Landing, NJ Posts: 11,787	Actually this is just the age-old confusion about the definition of a kilobyte/megabyte/gigabyte. In reality, a kilobyte is 1024 bytes (not 1,000) and a megabyte is 1,048,576 bytes (not 1,000,000) and a gigabyte is 1,073,741,824 bytes. Divide 300 by 1.074 and you get 279.33, which is what the Finder is telling you. This has been a source of confusion for everybody since the days of multi-megabyte disks! Disk Utility will tell you the full story. For example, if I look at a 100GB drive on my own system it reports: 93.16 GB (100,030,242,816 Bytes). Naturally, drive manufacturers use the math which makes their drives appear larger (eg: number of bytes and not the true definition of a Gigabyte).

February 24th, 2005, 05:19 PM	#4
Boyd Ostroff Wrangler Join Date: Dec 2002 Location: Mays Landing, NJ Posts: 11,787	Rhett: looks like we posted at the same time... Look at my math, that's all that's happening. I think the space used for directories on a 300 GB drive is trivial, certainly not 21 GB!

February 24th, 2005, 08:42 PM	#5
Rhett Allen Major Player Join Date: Mar 2002 Location: Plano, TX Posts: 607	Nice math there Boyd! I knew there was a divisor in there somewhere. I just always rounded it to 10% because I'm math-lazy (at least about some things). I don't know why they don't just make the drives OVER-sized so it comes out to 300Gig (or whatever they're claiming) after it's formatted, otherwise it's kind of misleading advertising.

February 25th, 2005, 07:47 AM	#6
Greg Boston Wrangler Join Date: Oct 2003 Location: DFW area, TX Posts: 6,117 Images: 1	I am looking at the same drive and am glad that it works ok. It has a 16mb cache as well. Evan, can you give some info about how well it is working in your system? Thanks, -gb-