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Re: Mass storage sizes

From Urs Thuermann <urs@isnogud.escape.de>
Newsgroups linux.debian.user
Subject Re: Mass storage sizes
Date 2025-01-10 03:00 +0100
Message-ID <K3ctz-7e56-1@gated-at.bofh.it> (permalink)
References (6 earlier) <K2k09-6rpc-1@gated-at.bofh.it> <K2kjv-6rL6-7@gated-at.bofh.it> <K2nhn-6tz5-5@gated-at.bofh.it> <K2pVU-6vir-11@gated-at.bofh.it> <K2pVU-6vir-9@gated-at.bofh.it>
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Michael Stone <mstone@debian.org> writes:

> On Tue, Jan 07, 2025 at 02:59:47PM -0700, Charles Curley wrote:
> >Mr. Tarsnap forgets something. The reason disks are addressed in powers
> >of two has to do with mathematics. Every hard and floppy disk out there
> >has flaws. To get around that, data is divided into sectors, and
> >checksums calculated. Done right, this allows for error correction for
> >small flaws. The math works out better if you do it in chunks that are
> >integer powers of two. So floppy disks have sectors of 256 octets, and
> >their attendant checksums. Modern hard drives schlep data in chunks of
> >4096 (2^12) octets. And bytes these days are eight bits.
> 
> The thing is, nobody cares about all that. It's an implementation
> detail that matters not to any normal person. Normal people care about
> things like "when I just look at the first couple of numbers of the
> size in bytes, is it the same thing as the size in <insert large unit>
> or do I need to do a bunch of math to answer a simple question?"
> 
> >GB or GiB? I don't care, just be clear which one you are using.
> 
> Which nobody is. The right answer is to stop using power of two units
> because they are pointless.

No matter how often you repeat this, it's still wrong.  Using power of
two units is quite useful.  For example, my computers had 5.12 kB,
65.356 kB, 16.777216 MB, 67.108864 MB, 268.435456 MB, 1.073741824 GB,
and 8.589934592 GB of RAM.  Perfectly correct, but I prefer to say
they had 5 kiB, 64 kiB, 16 MiB, 64 MiB, 256 MiB, 1 GiB, and 8 GiB of
RAM.  Because of technical reasons, rows and columns with m RAS and n
CAS select lines, sizes of RAM chips are almost always 2**m * 2**n
bytes, i.e. powers of 2.  RAM modules for the RAM slots of your
mainboard also are sized in powers of 2, because otherwise it would be
extremely hard to decode a memory address from the CPU into module
slot number and offset inside the module.

Block devices like floppy disks, hard disks, SSDs, etc. also have
block sizes which are powers of 2, like 256, 512, and 4096 bytes.
This is not because of checksumming as was suggested in this thread,
but because it makes it easier (e.g. for DMA controllers) to copy
from/to pages of RAM.

Therefore, my floppy disks had exacty 170.75 kiB, 720 kiB, and 1.44
MiB --- or as you would like to put it --- 174.848 kB, 737.280 kB, and
1.47456 MB.  So again: Are kiB, MiB, GiB, and TiB really pointless?

This is not really confusing, except for people who are too dumb to
understand units and their conversions.  Granted, some confusion came
from using k, M, G for the power-of-2 based units.  Back in the days
when we had only kilobytes this didn't matter too much since 2**10 is
so close to 1000 (only 2.4% more) that it was just practical to use
uppercase K to mean "a little more than k", i.e. 2**10, but still
speak of kilobytes.  When we reached sizes of megabytes, we couldn't
use a "larger than M letter", so M was simply used for both, 10**6 and
2**20, but it was usually clear from the context, what was meant.
Some confusion started, when some marketing people switched from using
the then common binary units to using decimal units because it made
their drives look larger than the competitor's drives.

Only much much later someone invented the ki, Mi, Gi, ... prefixes
to fix this and which I think helped a lot.  Only, when talking I
never hear anyone saying kibi, mebi, gibi, tebi. so you still need to
take the context into account to understand.

urs

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      Re: new computer arriving soon "Roy J. Tellason, Sr." <roy@rtellason.com> - 2024-12-22 02:20 +0100
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            Re: new computer arriving soon Marc Shapiro <marcnshap@gmail.com> - 2024-12-31 05:10 +0100
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                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
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                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
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                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
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                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
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              Re: new computer arriving soon Max Nikulin <manikulin@gmail.com> - 2025-01-02 04:10 +0100
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          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
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