Ubuntu Policy: prefixes for multiples of units

Martin Pitt martin.pitt at ubuntu.com
Sun Sep 28 11:44:51 BST 2008

Luke L [2008-09-24 20:26 -0500]:
> I agree in that the marketing dept. is irrelevant. We should put down
> what is factual. If a hard drive has a capacity of 298 "GiB" (what my
> "320GB" reports as), it should show up that way.

Hard drives should actually be displayed in GB, not in GiB IMHO.
Hardware vendors use GB, and powers of ten are just familiar to
everyone, so we should only use MiB/GiB where it is conformant to what
the hardware industry uses (like RAM size).

I actually made the test and asked my wife and my sister: "How many
tons/pixels/bytes do the following things have:

  2 Mt of cargo  (answer: 2,000,000 tons)
  6 MPixel digicam (answer: 6,000,000 pixel)
  100 GB hard drive (answer: 100 billion characters)
  2 MB of RAM (answer: 2,000,000 characters)

Both actually got quite confused when I told them that 2 M != 2M for
the RAM case. My sister is pretty technology averse and she didn't
even get the reasoning why we use powers of two for RAM. My wife did
(she is a pretty advanced user, but not a programmer/geek at all), but
she said that she was pretty confused about using "mega" for something
that is not a million. I wrote down "512 MiB" and asked her how to
interpret that. She read it as "512 Megabyte" and said "it's probably
something different, but I don't know".

So, I don't think we can please folks who don't know about the
power-of-two quirk in RAM in any meaningful way, but I do think that
using standard prefixes in a deliberately wrong context is worse than
using the new prefixes.

> On the subject of prefixes: Someone has to start it. While I
> personally don't like the way gibibit, mibibit, yibibit, etc. rolls
> off the tongue, it is more accurate for our purposes.

I expect that folks will actually continue to pronounce them as "two
Gigs of RAM", or just say "Gigabyte", but will hopefully start writing
it as "GiB" (that actually looks pretty nice in a written form IMHO).

Just the same way as everyone says "calories", actually means "kcal",
and should *actually* use kJ. :-)

Martin Pitt                        | http://www.piware.de
Ubuntu Developer (www.ubuntu.com)  | Debian Developer  (www.debian.org)

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