bootable ext. USB SSD for backup

Valeri Galtsev galtsev at
Fri Mar 17 15:41:49 UTC 2017

On Fri, March 17, 2017 10:22 am, Matthew Seaman wrote:
> On 2017/03/16 20:29, Valeri Galtsev wrote:
>> On Thu, March 16, 2017 3:13 pm, Ralf Mardorf via freebsd-questions
>> wrote:
>>> On Thu, 16 Mar 2017 14:56:07 -0500 (CDT), Valeri Galtsev wrote:
>>>> Junior programmer faithfully thinks that one kilobyte is exactly 1000
>>>> bytes.
>>>> Senior programmer faithfully thinks that one kilogram is exactly 1024
>>>> grams.
>>> When I programmed Commodore 64 Assembler a KB was 1024 B, nowadays I
>>> call it a KiB, to distinguish between 2^10 and 10^3, see
>>> .
>>> I dislike this joke, since senior programmers usually are also senior
>>> electronics technicians,
>> Right, I've heard the joke in a different language, so I had to make up
>> some equivalent for "computer geek" and otherwise person. Sysadmin
>> doesn't
>> fit there too as,e.g. myself, I have two degrees: electical engineering
>> and computer science, so megaohms, and kilovolts are kind of there. So,
>> I
>> don't know what to call the person so torn off the real life (as I heard
>> the joke in metric based country, where "kilo-" is used everywhere).
> I, for one, welcome our new SI / NIST overlords.
> But then I started out as a scientist, and the fact the the SI prefixes
> (p n µ m 1 k M G P etc.) always indicate powers of 10^3 is engraved on
> my soul.

I spent quite a bit of my life as scientist either... But I was always
"computer guy" either. And incidentally, according to wikipedia:

byte (8 but chunk of information) was deliberalety spelled with the "y" to
avoid transformation into bit... But I like how it sounds. As, my hunch is
they had that sort of humor by naming it byte which sounds exactly as
bite: as much of it as you can bite off the pie - or off the information
flow - to digest it in one go. Incidentally, does anybody still remember
the name for half of the byte? Yes, nibble! Also mentioned in the same
wikipedia article. It never mentions the fun I find in naming of byte and
nibble. You nibble it twice and you get as much as with one bite ;-)


> For anyone unclear as to why this is a good idea, consider the
> statement: "we peaked at 1.1Gb/s transfer rate."  That's computery stuff
> right?  So it really means 1181116006.4b/s doesn't it?
> Nope.  Bandwidth has always been measured in strict SI units -- mostly
> because it was physicists, electrical engineers and radio technicians
> got there first, and there's the Fourier relation between 'bits
> (samples) per second' and 'maximum signal frequency' that makes no sense
> at all if you start throwing powers of 2^10 around.  (Google for
> 'Nyquist sampling theorem' if you're interested).
> Now work out how long it's going to take to transmit 10GB of data
> (assume packet overhead is already included...) at that rate.  Easy
> enough (remember that 1B (byte) = 8b (bits) though.) Or did I mean 10GiB
> of data?
> It's this sort of confusion that leads to embarrassing mistakes like
> your Mars orbiter enjoying some unscheduled lithobraking[*].
> And, for an encore, if anyone could bring me the head of what ever
> bright spark in Electricity generation thought that the bastard mongrel
> of a unit 'kWh' was a good idea, I'd be forever in your debt.  It's a
> daft unit, when there is a perfectly acceptable and rigorous SI
> alternative which is even right around the same order of magnitude: the
> MegaJoule. 1 kWh is 3.6 MJ.
> 	Cheers,
> 	Matthew
> [*] OK, that was down to American Imperial vs SI units, but that is
> exactly the same sort of stupidity.

Valeri Galtsev
Sr System Administrator
Department of Astronomy and Astrophysics
Kavli Institute for Cosmological Physics
University of Chicago
Phone: 773-702-4247

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