[illys]

Pretty nice table here: https://en.wikipedia.org/wiki/Metric_prefix

"(...) he had the idea for the update when he saw media reports using unsanctioned prefixes for data storage such as brontobytes and hellabytes. (...)" and "The only letters that were not used for other units or other symbols were R and Q"

So it seems the new prefixes are partly initiated by the exponential computer storage needs rather than scientific needs. So they might need to move again soon. However the SI has exhausted the available stock of letters. Maybe Greek letters next time like micro for 10^-6.

Anyway does it really matter for IT people? I have seen so many people mixing up bit and byte, milli- and mega- as well. There are countless usages of mb all over the Internet to express MB.

[iquerno]

The only use cases I have seen for units larger than 'petabyte' are those representing the maximum allowed file sizes for ZFS, Btrfs and such. I also don't see a point in inventing more prefixes so that statisticians don't have to use scientific notation for large numbers. What use is that? How many people know how much a yottabyte is? If they need to Google the answer, that defeats the point.

1e12 terabytes seems easier to digest than 1 whatever-the-hell-,-I-don't-know-what-this-unit-is-meant-to-represent-byte. Not to mention, easier to read.

[saltcured]

Hmm, why would you mix 1e12 terabytes instead of saying 1e24 bytes? Why do we talk about 200k USD salaries instead of 2e5 USD? Or why isn't a US postage stamp marked as 6e-1 USD?

Also: in the past 25 years, "tera-scale" (TB and TFLOP) went from a prognostication about future high-performance computing into something you find in affordable consumer products. When campus computing centers are now deploying hundreds of petabytes, it seems myopic to think the PB threshold is anything but a signpost flying by the window...

[rjbwork]

>200k USD salaries instead of 2e5 USD?

You mean 2 lakh USD?

:D

[titzer]

$MEGACORP measures internal disk storage capacity in exabytes.

[Spivak]

Yes but translate this statement to the 80s and you might have said the same about giga.

[gregmac]

Do we need to have a single letter? Is it acceptable to combine prefixes?

Eg: 1 QB (quettabyte) == 1,000,000 YB (yottabytes) == 1 MYB (mega-yottabyte)

Without the new prefixes, we could have gone to 1 YYB (1,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000, or 10^48 bytes)

[allanrbo]

That is almost like reinventing something like Roman numerals :-) Maybe better to stick with 1e48 notation after all.

[silisili]

It's kinda funny that you mention it. If we say to someone '99 hundred', they'd immediately understand it as 9,900. If we say 'hundred hundred', it's an immediate math problem trying to figure out how many zeros and what it's called. At least, that's how I'd react.

[hypertele-Xii]

> If we say to someone '99 hundred', they'd immediately understand it as 9,900.

That's definitely untrue. In my native language we never mix tens and hundreds, and it always takes me a moment to parse that "thirteen hundred" means one thousand and three hundred.

[silisili]

Ah, I should have specified in the US. It's more common to say numbers between 100 and 10k as hundreds, unless it's exactly on a thousand. I think most people would say nineteen hundred, or 21 hundred for 1900 and 2100, but nobody would say 20 hundred for 2000(except for military time).

[halper]

SI prefixes could originally be combined like that: it was perfectly fine to say one hectokilometre. Such usage is now deprecated, though. You'd have to say 0.1 megametre instead.

[Asraelite]

Does anyone know why they chose "ronna" instead of "renna"? It should be r + ennea (Greek for nine), so where does the "o" come from?

Every prefix up until now has been consistent about the first vowel mirroring the Greek word:

  tetra -> tera
  penta -> peta
  hex -> exa
  hepta -> zetta
  okto -> yotta

[labster]

Uppercase MB is megabytes, lowercase mb is millibars. Both can go through a series of tubes, but millibars are also useful in dump trucks, to make the wheels go round and round.

[IshKebab]

Millibars is mbar not mb.

[labster]

I’m a meteorologist. Most of the time no one bothers to spell out mbar, and just uses mb in both scientific papers and operational data.