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Hard drive size only 87.9gb when label states 100gb

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March 14, 2010 1:40:24 PM

Seagate ATA 100 maybe Barracuda; label on drive says 100gb but Windows reports it at 80gb and Linux reports it at 87.9gb. Whuh b up wih dat? Dern dementia... I can remember the size label but not if it was a Barracuda or not...
I think it was even advertised as an 80gb OEM new drive.
Can't find Linux command for identifying the drive without going through the hassle of pulling it from case. Only thing I can think of is either a factory second or some of the 100gb was marked bad at factory.
I guess they'z both the same thang. Thanx for any explanation on size discrepancy! I already calculated the mb vs gb size difference and numbers don't match zacktly....
March 14, 2010 6:56:05 PM

I have a hard time understanding the logic:
"gigabyte" customarily means 1073741824 bytes.
100x 1,073,741,824= 107,374,182,400” ...
“SI prefixes in the same way, so the purchaser of a "500 GB" hard drive would find the operating system showing it as that and not "477 GB"
above …. quoted from the article

The drive case label does not say “107,374,182,400 bytes” it says 100gb
and Linux Disk size analyzer says 87.9GB. Windoze was reporting it as 80GB. I read the article before posting and after receiving a reply and I still did not find the explanation for size difference.

If a 500gb drive registers as 477 then a 100gb should register as 95.4
according to these statements if I understand it correctly I should have a drive stated size in the OS as 95.4gb and not 87.9GB in Linux and 80GB Windoze.
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a c 127 G Storage
March 14, 2010 7:19:34 PM

500GB drives register as 465GiB or 500GB.

If kilo means 1000, and mega means million, and giga means billion; then this doesn't conform to the binary-power-of-two scheme where you get values like 1024. So that's why the binary prefix was presented.

So 1GB = 1000 x 1000 x 1000 = 1000000000 bytes
1GiB = 1024 x 1024 x 1024 = 1073741824 bytes = 7.3% more
1TiB = 1024 x 1024 x 1024 x 1024 = 1099511627776 bytes = 10% more

etc.

So your 100GB disk should be recognised as 93,13GiB. However, i only know 80GB or 120GB HDDs; are you sure its a 100GB disk?

Since both your values you get in Windows are off, can you post a screenshot of Windows disk management screen? Or Ubuntu's GParted Partition Editor output?
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March 14, 2010 7:53:28 PM

I have to reinstall the drive to use Windows and I cannot find GParted in Ubuntu's 9.04 menus and I've never done [don't know how to do] a screen shot in either also. Yes handicapped to hilt with memory problems--sorry to dump here-- but understanding that ought to relieve some frustration. I'll remove drive in question and make sure memory didn't play tricks on me by writing down make, model, and size....
If you care to chime in and tutor me through screen shots I'll work toward that end. Other wise it may be days or weeks befor I 'giterdunn' I no longer work at light speed due to my dementia and I may fizzle out and forget to get this done at all in the mean time....
So here goes shut down and remove drive coming up. Then I'll log in again and report that info.
Also the only way I've use GParted is from a Livecd and very uncertain how to screen shot from there also. I guess if that is the way it has to be done all I would have to do is somehow then attach the screen shot a reply message on toms hardware site. Apology for my ignornance!!!
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March 14, 2010 8:34:35 PM

OK m back!
Took longer to refind this post than it did to pull and reinstall drive. It's a Seagate Barracuda 7200.7 Ultra ATA 100 Gbytes
Model#ST310011A
S/N:4LHOSX37
Firmware 3.02

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March 14, 2010 8:55:48 PM

O.K. I remembered that I might have to install GParted and checked and yes had to that and did so. Got in there and in GParted>devices>/dev/sda it shows 93.16 GiB and /dev/sda1 shows 89.336 GiB with Extended and Swap each measuring 3.83 Gib. Dis splainz volumes %:) )) thankz fur the patience and the kickstart.
Ain't figgered out how to screen shot yet but faintly remember that it could be a series of keystrokes and hadn't the time or Fizzle left to research it but the outcome of this all is solved me thinkz!!!
Thank you very much and kudos for your effortz....%:])SW
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March 14, 2010 8:59:03 PM

Best answer selected by sweetwater.
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a c 115 G Storage
March 14, 2010 9:30:38 PM

HD manufacturers decided they could make their products look bigger by switching to base 10 counting whereas as we all know everything else in computers is base 2. WD paid out big bucks as part of a class action settlement back in 2006 over this tactic......now all HD manufacturers have to label their packaging explaining how they count different.

As far as I am aware, RAM, Flash media, everything else in computing still uses Base 2 math for quantifying size.
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a c 127 G Storage
March 15, 2010 2:23:03 AM

Alright so your 100GB disk is really 93,16GiB (a little more than the official "93,13GiB). On that 93,16GiB you have a 89GiB partition; so you could make the partition larger still, if you care about the lost space. Generally, the last portion of the HDD is very slow. You may not even wish to bother using it.

Some drivers, like Velociraptor and server-class HDDs, actually do not use all their capacity; only the fastest spots. In essence, these disks are 'short-stroked' by design.
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a c 127 G Storage
March 15, 2010 2:28:07 AM

JackNaylorPE: i agree with you, it was just a filthy industry trick to advertise bigger numbers.

But in computing technology, 1000 and 1024 are being mixed all the time. You need to know when you're using base-10 (1000) and when you're using base-2 (1024). For this purpose, the difference between GB and GiB is adequate i believe. If it passes on, anyway. Linux does, but Windows 7 still reports it the 'wrong' way.

When you might have thought the 1000/1024 thingy would go away with SSDs; its not. They use the extra 7-10% capacity for internal use, for performance and longetivity reasons. That's actually useful and desirable, and you may even want to dedicate more space reserved for internal use. But it still does mean you don't have 128/256/512/1024GiB disks.
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