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When 1 GB Is Really 0.9313 Gigabytes

Posted by timothy on from the internal-struggle dept.

An anonymous reader writes "When it comes to RAM, as every geek knows, 1 GB does not mean 1 billion bytes.. it means 2**30 (1,073,741,824) bytes. However, several decades ago "they" decided that GB, MB, and KB would be interpreted differently when it comes to disk drives; 1 GB means exactly 1 billion bytes. Ed Bott points out that Microsoft's marketers and Windows kernel developers aren't on the same page when it comes to these units: the marketers use the more generous decimal interpretation, while Windows measures and reports capacity using the binary (2**30) measure. Careful customers who bother to check what they've got have been known to get peeved by the discrepancy."

4 of 618 comments (clear)

  1. Terabytes by Janek+Kozicki · · Score: 5, Informative
    It gets worse when you start counting terabytes. I recently bought a 2TB HDD and grown my mdadm raid array using:

    mdadm --add /dev/md69 /dev/sde3
    mdadm --grow --bitmap=none /dev/md69
    mdadm --grow --raid-devices=5 --backup-file=/root/grow_md69.bak /dev/md69
    mdadm --grow --bitmap=internal --bitmap-chunk=65536 /dev/md69
    resize2fs /dev/md69

    And I was surprised that my filesystem grew only by 1800 GB ! Still a bit more space for rsnapshot cron backing up all my family's PCs twice per day. But still... I wanted 2TB more, not 1.8TB.

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  2. GiB by Anonymous Coward · · Score: 5, Informative

    Finally adopt the official prefixes.
    If you are talking decimal, use GB. If you are talking binary, use GiB.

  3. Re:"they" can fuck off, the binary units are the o by dingen · · Score: 5, Informative

    Actually, when it comes to correctness: the International System of Units defines kilo-, mega- and giga- as powers of 10 instead, not powers of 2. I think it is much clearer for a user to define a megabyte as a million bytes. How memory is handled inside a computer is something developers care about, no user should be bothered with it. So all in all I agree with the marketing-people, albeit for different reasons.

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    Pretty good is actually pretty bad.
  4. Re:"they" can fuck off, the binary units are the o by gomiam · · Score: 5, Informative

    I don't know about hearing, but I have read GiB and MiB at the Linux kernel logs since quite a long time.