[sf-lug] drive sizes/capacities: Re: Want a large Flash Drive or a good sized SSD?

[Bobbie Sellers]

Well when you are correct, Michael,
you are correct.
128 GB Flash Drive = 117.x GiB

     Bobbie

On 1/14/19 10:44 PM, Michael Paoli wrote:
> Blame it (mostly) on marketing - and consumers not demanding better.
>
> I think you've got that also about bass ackwards.
>
> 128 GiB !~= 117 GB
> It's more like the other way around:
> 128,000,000,000 bytes =~ 119.209289550781 GiB
>
> https://en.wikipedia.org/wiki/Binary_prefix
> https://en.wikipedia.org/wiki/Metric_prefix
>
> And, why would marketing/sales do that?  Because it "sounds"
> bigger (but isn't) and cost them less to make (less bytes).
>
> Let's look at the #s, and % comparing decimal to binary:
> $ perl -e 'for(1..5){my $i=(10**3)**$_;my $b=(2**10)**$_;print(join(q( 
> ),$i,$b,$i*100/$b.q(%),),"\n",);};'
> 1000 1024 97.65625%
> 1000000 1048576 95.367431640625%
> 1000000000 1073741824 93.1322574615479%
> 1000000000000 1099511627776 90.9494701772928%
> 1000000000000000 1125899906842624 88.8178419700125%
> $
>
> You can also look at the exact size of the device using the
> /sys filesystem ... though it will give you size in 512 byte
> blocks:
> $ (cd /sys/block && grep . /sys/block/sd[a-z]/size)
> /sys/block/sda/size:4004704368
> /sys/block/sdb/size:312581808
> $
>
> E.g., have a look at the drives on:
> https://www.wiki.balug.org/wiki/doku.php?id=balug:offered_wanted_hardware_etc 
>
> And notice a particular pattern ...
> what's marketed as 80GB is at or just a bit larger than
> 80*10^9 bytes, well short of 80*2^30 bytes.
> Likewise for 1TB:
> at or very slightly over 10^12 bytes, well short of 2^40 bytes,
> etc.
>
> That's also why the marketing materials tend to have their little
> CYA *, e.g. stuff like:
> 1TB*
> *TB=1,000,000,000,000 bytes
>
>> From: "Bobbie Sellers" <bliss-sf4ever at dslextreme.com>
>> Subject: [sf-lug] Want a large Flash Drive or a good sized SSD?
>> Date: Mon, 14 Jan 2019 10:45:22 -0800
>
>>     Well the drives of course are not quite as large as labeled
>> the 128 GiB USB Flash Drive comes in at 117.x Gigabytes but the
>> price is right.
>>     I bet the 128 and 240 GiB drives come in below the
>> labeled size but the prices are good.
>
>
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