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Groups > linux.debian.user > #276436

Re: Mass storage sizes (was: /dev/serial/by-id)

From Nicolas George <george@nsup.org>
Newsgroups linux.debian.user
Subject Re: Mass storage sizes (was: /dev/serial/by-id)
Date 2025-01-09 21:50 +0100
Message-ID <K37Dz-75oL-9@gated-at.bofh.it> (permalink)
References <K32DT-6VZ7-13@gated-at.bofh.it>
Organization linux.* mail to news gateway

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Michael Stone (12025-01-08):
> For example...let's take the 18000000000000B drive discussed earlier. That's
> 18TB or 16TiB. Annoying, but ok. Now that's also 18000MB but 16763MiB. And
> it's 18000000MB or 17166137MiB. So if you have a display in MB and you want
> to know the value in TB you move the decimal 6 places. But if you move the
> decimal 6 places to get from MiB to TiB you get...the wrong answer. Does
> this actually happen? Yes. All the freaking time. (A classic mashup is 1024k
> blocks expressed with power of 10 M and G.) Now this next part is important:
> no normal human working with files and disk space and trying to communicate
> with other normal humans calculates the values in base 8 or base 16.
> Communication of numbers between ordinary people generally happens in base
> 10. SI prefixes are base 10. And when you munge up some stupid base 2 units
> with what people want and expect to be base 10, mistakes and confusion
> happen. And the benefit of all that confusion and increased cognative load
> is: absolutely nothing.

The thing is, for people who _expect_ rather than _know_ about this, 10%
accuracy is plenty enough. Especially since, as has been pointed, a lot
of factors will conspire to reduce the space available in practice.

For the people who need exact figures, on the other hand, binary units
are much more convenient, not just to measure the size of memory
modules: alignment requirements, maximum sizes of files and devices,
size of stripes, they are all based on powers of two.


Stefan Monnier (12025-01-09):
> A related problem is when writing code which displays such sizes in
> a human readable way, for example a "speedometer" displaying the number
> of bytes per second with a limited amount of space.  A common choice is
> to use 3 chars for the number plus a unit, i.e. things like "254 kB/s"
> or "1.5 MB/s".  Now, if you use the "1024" multiplier, you get a funny
> quirk when the current speed is, say 1003 kB/s, because "1003 kB/s" uses
> one char too many, yet we haven't reached "1.0 MB/s" either.

Well, “1.5” is too few significant digits in the first place.

So, you start:

 100 M
 999 M
1000 M
1024 M
1.59 G
9.99 G
10.0 G
99.9 G
 100 G
 999 G
1000 G

The switch to the next prefix does not have to be as soon as the
mantissa is greater than one. Notice that the heights of mountains are
in meters, not in kilometers, even for the Himalaya. It is better to go
to 9999 M and only then switch to 9.77 G: more significant digits, not
less readable.

(Also, the people who designed the symbols for the prefixes really
dropped the ball with k instead of K, but that predates memory units by
a long time.)

-- 
  Nicolas George

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new computer arriving soon "Roy J. Tellason, Sr." <roy@rtellason.com> - 2024-12-21 18:50 +0100
  Re: new computer arriving soon "Andrew M.A. Cater" <amacater@einval.com> - 2024-12-21 20:30 +0100
    Re: new computer arriving soon Joe <joe@jretrading.com> - 2024-12-21 21:20 +0100
      Re: new computer arriving soon "Roy J. Tellason, Sr." <roy@rtellason.com> - 2024-12-22 02:20 +0100
    Re: new computer arriving soon "Roy J. Tellason, Sr." <roy@rtellason.com> - 2024-12-22 02:20 +0100
      UEFI, Export from Virtualbox [WAS Re: new computer arriving soon] "Andrew M.A. Cater" <amacater@einval.com> - 2024-12-22 09:50 +0100
      Re: new computer arriving soon "Roy J. Tellason, Sr." <roy@rtellason.com> - 2024-12-26 20:40 +0100
        Re: new computer arriving soon David Christensen <dpchrist@holgerdanske.com> - 2024-12-26 23:40 +0100
          Re: new computer arriving soon David Wright <deblis@lionunicorn.co.uk> - 2024-12-27 17:30 +0100
            Re: new computer arriving soon Marc Shapiro <marcnshap@gmail.com> - 2024-12-31 05:10 +0100
              Re: new computer arriving soon gene heskett <gheskett@shentel.net> - 2024-12-31 05:40 +0100
                Re: new computer arriving soon "Andrew M.A. Cater" <amacater@einval.com> - 2024-12-31 19:00 +0100
                Re: new computer arriving soon gene heskett <gheskett@shentel.net> - 2024-12-31 23:00 +0100
                Re: new computer arriving soon "Andrew M.A. Cater" <amacater@einval.com> - 2025-01-01 00:00 +0100
                Re: new computer arriving soon gene heskett <gheskett@shentel.net> - 2025-01-01 01:00 +0100
                Re: new computer arriving soon pocket@homemail.com - 2025-01-01 15:00 +0100
                Re: new computer arriving soon Frank Guthausen <fg.debian@shimps.de> - 2025-01-01 15:30 +0100
                Re: new computer arriving soon pocket@homemail.com - 2025-01-01 15:40 +0100
                Re: new computer arriving soon Michael Stone <mstone@debian.org> - 2025-01-01 16:40 +0100
                Re: new computer arriving soon pocket@homemail.com - 2025-01-01 17:20 +0100
                Re: new computer arriving soon Michael Stone <mstone@debian.org> - 2025-01-01 18:00 +0100
                Re: new computer arriving soon pocket@homemail.com - 2025-01-01 18:00 +0100
                Re: new computer arriving soon Max Nikulin <manikulin@gmail.com> - 2025-01-02 03:10 +0100
                Re: new computer arriving soon pocket@homemail.com - 2025-01-02 03:40 +0100
                Re: new computer arriving soon Charles Curley <charlescurley@charlescurley.com> - 2025-01-01 17:30 +0100
                Re: new computer arriving soon Michael Stone <mstone@debian.org> - 2025-01-01 18:20 +0100
                Re: new computer arriving soon gene heskett <gheskett@shentel.net> - 2025-01-01 22:00 +0100
                Re: new computer arriving soon Joe <joe@jretrading.com> - 2025-01-01 19:50 +0100
                Re: new computer arriving soon gene heskett <gheskett@shentel.net> - 2025-01-01 22:50 +0100
                Re: new computer arriving soon Andy Smith <andy@strugglers.net> - 2025-01-02 14:50 +0100
                Re: new computer arriving soon gene heskett <gheskett@shentel.net> - 2025-01-03 04:00 +0100
                Re: new computer arriving soon gene heskett <gheskett@shentel.net> - 2025-01-03 17:30 +0100
                Re: new computer arriving soon Andy Smith <andy@strugglers.net> - 2025-01-03 13:10 +0100
                Re: new computer arriving soon Max Nikulin <manikulin@gmail.com> - 2025-01-02 03:30 +0100
                Re: new computer arriving soon pocket@homemail.com - 2025-01-02 03:40 +0100
                Re: new computer arriving soon Max Nikulin <manikulin@gmail.com> - 2025-01-02 04:30 +0100
                Re: new computer arriving soon pocket@homemail.com - 2025-01-02 04:50 +0100
                Re: new computer arriving soon Max Nikulin <manikulin@gmail.com> - 2025-01-02 16:40 +0100
                Re: new computer arriving soon pocket@homemail.com - 2025-01-02 17:10 +0100
                Re: new computer arriving soon Max Nikulin <manikulin@gmail.com> - 2025-01-04 05:00 +0100
                Re: new computer arriving soon gene heskett <gheskett@shentel.net> - 2025-01-04 11:20 +0100
                Gene and networkmanager (was: Re: new computer arriving soon) Max Nikulin <manikulin@gmail.com> - 2025-01-05 04:50 +0100
                Re: Gene and networkmanager (was: Re: new computer arriving soon) gene heskett <gheskett@shentel.net> - 2025-01-05 17:20 +0100
                /dev/serial/by-id (was: Re: new computer arriving soon) Max Nikulin <manikulin@gmail.com> - 2025-01-05 05:00 +0100
                Re: /dev/serial/by-id (was: Re: new computer arriving soon) gene heskett <gheskett@shentel.net> - 2025-01-05 17:30 +0100
                Re: /dev/serial/by-id Max Nikulin <manikulin@gmail.com> - 2025-01-06 03:30 +0100
                Re: /dev/serial/by-id gene heskett <gheskett@shentel.net> - 2025-01-06 08:20 +0100
                Re: /dev/serial/by-id Max Nikulin <manikulin@gmail.com> - 2025-01-07 04:20 +0100
                Re: /dev/serial/by-id gene heskett <gheskett@shentel.net> - 2025-01-07 10:00 +0100
                Re: /dev/serial/by-id gene heskett <gheskett@shentel.net> - 2025-01-07 14:50 +0100
                Mass storage sizes (was: /dev/serial/by-id) Stefan Monnier <monnier@iro.umontreal.ca> - 2025-01-07 16:10 +0100
                Re: Mass storage sizes (was: /dev/serial/by-id) Dan Purgert <dan@djph.net> - 2025-01-07 16:50 +0100
                Re: Mass storage sizes eben@gmx.us - 2025-01-07 17:10 +0100
                Re: Mass storage sizes <tomas@tuxteam.de> - 2025-01-07 17:40 +0100
                Re: Mass storage sizes eben@gmx.us - 2025-01-07 18:00 +0100
                Re: Mass storage sizes Stefan Monnier <monnier@iro.umontreal.ca> - 2025-01-07 20:40 +0100
                Re: Mass storage sizes <tomas@tuxteam.de> - 2025-01-08 06:30 +0100
                Re: Mass storage sizes (was: /dev/serial/by-id) Michael Stone <mstone@debian.org> - 2025-01-07 17:10 +0100
                Re: Mass storage sizes (was: /dev/serial/by-id) Michael Stone <mstone@debian.org> - 2025-01-07 17:30 +0100
                Re: Mass storage sizes (was: /dev/serial/by-id) Dan Purgert <dan@djph.net> - 2025-01-07 18:10 +0100
                Re: Mass storage sizes (was: /dev/serial/by-id) Nicholas Geovanis <nickgeovanis@gmail.com> - 2025-01-09 04:10 +0100
                Re: Mass storage sizes (was: /dev/serial/by-id) Michael Stone <mstone@debian.org> - 2025-01-09 05:50 +0100
                Re: Mass storage sizes Stefan Monnier <monnier@iro.umontreal.ca> - 2025-01-09 16:30 +0100
                Re: Mass storage sizes Dan Purgert <dan@djph.net> - 2025-01-09 18:10 +0100
                Re: Mass storage sizes (was: /dev/serial/by-id) Nicolas George <george@nsup.org> - 2025-01-09 21:50 +0100
                Re: Mass storage sizes (was: /dev/serial/by-id) Michael Stone <mstone@debian.org> - 2025-01-10 00:50 +0100
                Re: Mass storage sizes (was: /dev/serial/by-id) Jeffrey Walton <noloader@gmail.com> - 2025-01-10 01:10 +0100
                Re: Mass storage sizes (was: /dev/serial/by-id) Timothy M Butterworth <timothy.m.butterworth@gmail.com> - 2025-01-10 02:10 +0100
                Re: Mass storage sizes (was: /dev/serial/by-id) Dan Purgert <dan@djph.net> - 2025-01-10 11:00 +0100
                Re: Mass storage sizes (was: /dev/serial/by-id) gene heskett <gheskett@shentel.net> - 2025-01-10 15:10 +0100
                Re: Mass storage sizes (was: /dev/serial/by-id) <tomas@tuxteam.de> - 2025-01-10 07:30 +0100
                Re: Mass storage sizes John Hasler <john@sugarbit.com> - 2025-01-10 15:50 +0100
                Re: Mass storage sizes eben@gmx.us - 2025-01-10 21:40 +0100
                Re: Mass storage sizes gene heskett <gheskett@shentel.net> - 2025-01-11 01:50 +0100
                Re: Mass storage sizes Jeffrey Walton <noloader@gmail.com> - 2025-01-11 01:40 +0100
                Re: Mass storage sizes (was: /dev/serial/by-id) Heriberto Avelino <heriberto.avelino@gmail.com> - 2025-01-10 01:30 +0100
                Re: Mass storage sizes Kushal Kumaran <kushal@locationd.net> - 2025-01-07 20:20 +0100
                Re: Mass storage sizes Nicolas George <george@nsup.org> - 2025-01-07 21:10 +0100
                Re: Mass storage sizes Michael Stone <mstone@debian.org> - 2025-01-07 23:10 +0100
                Re: Mass storage sizes Urs Thuermann <urs@isnogud.escape.de> - 2025-01-10 03:00 +0100
                Re: Mass storage sizes Michael Stone <mstone@debian.org> - 2025-01-10 05:30 +0100
                Re: Mass storage sizes Stefan Monnier <monnier@iro.umontreal.ca> - 2025-01-10 15:40 +0100
                Re: Mass storage sizes Charles Curley <charlescurley@charlescurley.com> - 2025-01-07 23:10 +0100
                Re: Mass storage sizes gene heskett <gheskett@shentel.net> - 2025-01-08 00:30 +0100
                Re: Mass storage sizes "Thomas Schmitt" <scdbackup@gmx.net> - 2025-01-07 17:40 +0100
                Re: Mass storage sizes Stefan Monnier <monnier@iro.umontreal.ca> - 2025-01-07 20:30 +0100
                Re: Mass storage sizes (was: /dev/serial/by-id) Jeffrey Walton <noloader@gmail.com> - 2025-01-09 08:40 +0100
                Re: /dev/serial/by-id Max Nikulin <manikulin@gmail.com> - 2025-01-08 04:00 +0100
                Re: /dev/serial/by-id Max Nikulin <manikulin@gmail.com> - 2025-01-08 04:10 +0100
                Re: /dev/serial/by-id Anssi Saari <anssi.saari@debian-user.mail.kapsi.fi> - 2025-01-07 11:20 +0100
                Specific mdadm instructions for Gene [WAS Re: new computer arriving  soon] "Andrew M.A. Cater" <amacater@einval.com> - 2025-01-02 17:00 +0100
                Re: Specific mdadm instructions for Gene [WAS Re: new computer  arrivingsoon] gene heskett <gheskett@shentel.net> - 2025-01-02 23:10 +0100
                Re: Specific mdadm instructions for Gene [WAS Re: new computer  arrivingsoon] Andy Smith <andy@strugglers.net> - 2025-01-02 23:20 +0100
                Re: Specific mdadm instructions for Gene [WAS Re: new computer  arrivingsoon] Nicolas George <george@nsup.org> - 2025-01-02 23:30 +0100
                Re: Specific mdadm instructions for Gene [WAS Re: new computer  arrivingsoon] Michael Stone <mstone@debian.org> - 2025-01-03 00:10 +0100
                Re: Specific mdadm instructions for Gene [WAS Re: new computer arrivingsoon] Jeffrey Walton <noloader@gmail.com> - 2025-01-03 04:00 +0100
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                Re: Specific mdadm instructions for Gene [WAS Re: new  computerarrivingsoon] Max Nikulin <manikulin@gmail.com> - 2025-01-04 04:30 +0100
                Re: Specific mdadm instructions for Gene [WAS Re:  newcomputerarrivingsoon] gene heskett <gheskett@shentel.net> - 2025-01-04 04:50 +0100
                sgdisk missing under Armbian for Gene [WAS Specific mdadm  instructions for Gene] "Andrew M.A. Cater" <amacater@einval.com> - 2025-01-03 12:40 +0100
                Re: sgdisk missing under Armbian for Gene [WAS Specific mdadm  instructions for Gene] Nicolas George <george@nsup.org> - 2025-01-03 12:50 +0100
                Re: sgdisk missing under Armbian for Gene [WAS Specific  mdadminstructions for Gene] gene heskett <gheskett@shentel.net> - 2025-01-03 17:40 +0100
                Re: new computer arriving soon Max Nikulin <manikulin@gmail.com> - 2025-01-02 04:00 +0100
                Re: new computer arriving soon gene heskett <gheskett@shentel.net> - 2025-01-02 05:30 +0100
                Re: new computer arriving soon George at Clug <Clug@goproject.info> - 2025-01-02 08:30 +0100
                Re: new computer arriving soon Michael Stone <mstone@debian.org> - 2025-01-02 23:40 +0100
                Re: new computer arriving soon fxkl47BF@protonmail.com - 2025-01-02 23:50 +0100
                Re: new computer arriving soon George at Clug <Clug@goproject.info> - 2025-01-03 00:00 +0100
                Re: new computer arriving soon Michael Stone <mstone@debian.org> - 2025-01-03 00:20 +0100
                Re: new computer arriving soon George at Clug <Clug@goproject.info> - 2025-01-03 00:50 +0100
                Re: new computer arriving soon "Roy J. Tellason, Sr." <roy@rtellason.com> - 2025-01-03 17:00 +0100
                Re: new computer arriving soon Michael Stone <mstone@debian.org> - 2025-01-03 17:20 +0100
                Re: new computer arriving soon David Wright <deblis@lionunicorn.co.uk> - 2025-01-10 05:50 +0100
                Re: new computer arriving soon Greg Wooledge <greg@wooledge.org> - 2025-01-03 00:10 +0100
                Re: new computer arriving soon George at Clug <Clug@goproject.info> - 2025-01-03 00:00 +0100
                Re: new computer arriving soon Michael Stone <mstone@debian.org> - 2025-01-03 00:00 +0100
                Re: new computer arriving soon  George at Clug <Clug@goproject.info> - 2025-01-03 00:40 +0100
                Re: new computer arriving soon Andy Smith <andy@strugglers.net> - 2025-01-03 00:50 +0100
                Re: new computer arriving soon "Roy J. Tellason, Sr." <roy@rtellason.com> - 2025-01-03 17:00 +0100
                Re: new computer arriving soon Max Nikulin <manikulin@gmail.com> - 2025-01-02 16:30 +0100
              Re: new computer arriving soon Frank Guthausen <fg.debian@shimps.de> - 2024-12-31 20:20 +0100
              Re: new computer arriving soon Max Nikulin <manikulin@gmail.com> - 2025-01-02 04:10 +0100
                Re: new computer arriving soon Michael Stone <mstone@debian.org> - 2025-01-02 23:50 +0100
                Re: new computer arriving soon Marc Shapiro <marcnshap@gmail.com> - 2025-01-06 06:10 +0100
          Re: new computer arriving soon "Roy J. Tellason, Sr." <roy@rtellason.com> - 2024-12-27 20:20 +0100
  Re: new computer arriving soon George at Clug <Clug@goproject.info> - 2024-12-22 00:40 +0100
    Re: new computer arriving soon "Roy J. Tellason, Sr." <roy@rtellason.com> - 2024-12-22 02:30 +0100
      Re: new computer arriving soon George at Clug <Clug@goproject.info> - 2024-12-22 05:50 +0100
  Re: new computer arriving soon songbird <songbird@anthive.com> - 2024-12-22 17:20 +0100

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