Iron Wolf 12TB actually 11???

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Iron Wolf 12TB actually 11???

Post by Kopy78 » Thu Aug 23, 2018 1:07 pm


We just purchased an 873e and 8 x 12TB Iron Wolf drives. After inserting them in the NAS it seems to think they're 11176GB, which is 10.9TB....Does anybody know why this is?

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Re: Iron Wolf 12TB actually 11???

Post by OneCD » Thu Aug 23, 2018 1:30 pm

Hi and welcome to the forum.

Wikipedia wrote:In the context of computer memory, gigabyte and GB are customarily used to mean 1024^3 (2^30) bytes, although not in the context of data transmission and not necessarily for hard drive size.

Hard drive and SSD manufacturers use the gigabyte to mean 1000000000 bytes. Therefore, the capacity of a 128 GB SSD is 128000000000 bytes. Expressed in gibibytes this is about 119.2 GiB.

12 TB = 12,000,000,000,000 bytes / (1024^3) = 11,175.87 GiB

Looks fine to me. :geek:


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Re: Iron Wolf 12TB actually 11???

Post by Bob Zelin » Fri Aug 24, 2018 3:02 am

you will be happy to know that a 10TB drive is actually 9.1 TB from all manufacturers. A 6TB drive is 5.46 TB.
That's marketing for you !

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Re: Iron Wolf 12TB actually 11???

Post by storageman » Fri Aug 24, 2018 4:50 pm

Bob Zelin wrote:you will be happy to know that a 10TB drive is actually 9.1 TB from all manufacturers. A 6TB drive is 5.46 TB.
That's marketing for you !

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You're buying exactly the number of bytes you pay for, there is no marketing con here! Just user lack of knowledge.
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Re: Iron Wolf 12TB actually 11???

Post by seagate_surfer » Sat Sep 08, 2018 1:14 am

Hello Kopy78,

Hard drive manufacturers market drives in terms of decimal (base 10) capacity. In decimal notation, one megabyte (MB) is equal to 1,000,000 bytes, one gigabyte (GB) is equal to 1,000,000,000 bytes, and one terabyte (TB) is equal to 1,000,000,000,000 bytes.

Programs such as FDISK, system BIOS, Windows, and older versions of macOS use the binary (base 2) numbering system. In the binary numbering system, one megabyte is equal to 1,048,576 bytes, one gigabyte is equal to 1,073,741,824 bytes, and one terabyte is equal to 1,099,511,627,776 bytes.

Simply put, decimal and binary translates to the same amount of storage capacity.

You can read more about storage capacity measurement standards here.
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Re: Iron Wolf 12TB actually 11???

Post by fribse » Sat Nov 10, 2018 4:54 pm

Yes, it is a con, but a well known one, there is a set definition of what a kilo-/mega-/giga-/tera-/petabyte is, it counts in hexadecimal. This is just the way it is. This is the way it's defined in computerscience.
But HD manufacturers like to pump the numbers (started about 20 years ago), so they just decided to take the mathematical definition of the words, instead of the computer definition.
This produces the discrepancy between what a computer reports, and what a manufacturer repors.
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Re: Iron Wolf 12TB actually 11???

Post by Thisisnotmyname » Thu Nov 22, 2018 7:50 am

As others have stated, back in the late 90s hard drive manufacturers realized they could make drives sound bigger if they started treating the units in multiples of 10 rather than multiples of 2 (which had always been the standard). So a 8.2 GB drive (as an example) all the sudden only had to be 8,200,000,000 bytes rather than 8,804,682,956 bytes. Consumers who didn't know any better would still buy the drive thinking it was whatever multiple of the drive size they were replacing and effectively cheaper per MB than it otherwise would be. The larger the drives get the bigger that multiple differential gets so drive manufacturers can keep on advertising much larger capacities than the way systems treat them. That's stuck so now we all get base 10 sized drives from marketing departments that appear smaller in base 2 terms when we install them. Those who know this have also started using nomenclature of GiB vs GB (and MiB vs MB) to denote true base 2 sizes from marketing driven base 10 sizes.

Long story short, any drive you buy will have a lower base 2 capacity than what you saw on the box.

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