# Re: what is our answer to ZFS?

From: Rob Landley
Date: Tue Nov 22 2005 - 00:47:17 EST

On Monday 21 November 2005 14:02, Bernd Petrovitsch wrote:
> On Mon, 2005-11-21 at 12:52 -0600, Rob Landley wrote:
> [...]
>
> > couple decades from now. It's also proposing that data compression and
> > checksumming are the filesystem's job. Hands up anybody who spots
> > conflicting trends here already? Who thinks the 128 bit requirement came
> > from marketing rather than the engineers?
>
> Without compressing you probably need 256 bits.

I assume this is sarcasm. Once again assuming you can someday manage to store
1 bit per electron, it would have a corresponding 2^256 protons*, which would
weigh (in grams):

> print 2**256/(6.02*(10**23))
1.92345663185e+53

Google for the weight of the earth:
http://www.ecology.com/earth-at-a-glance/earth-at-a-glance-feature/
Earth's Weight (Mass): 5.972 sextillion (1,000 trillion) metric tons.
Yeah, alright, mass... So that's 5.972*10^18 metric tons, and a metric ton is
a million grams, so 5.972*10^24 grams...

Google for the mass of the sun says that's 2*10^33 grams. Still nowhere
close.

Basically, as far as I can tell, any device capable of storing 2^256 bits
would collapse into a black hole under its own weight.

By the way, 2^128/avogadro gives 5.65253101198e+14, or 565 million metric
tons. For comparison, the empire state building:
http://www.newyorktransportation.com/info/empirefact2.html
Is 365,000 tons. (Probably not metric, but you get the idea.) Assuming I
haven't screwed up the math, an object capable of storing anywhere near 2^128
bits (constructed as a single giant molecule) would probably be in the size
ballpark of new york, london, or tokyo.

2^64 we may actually live to see the end of someday, but it's not guaranteed.
2^128 becoming relevant in our lifetimes is a touch unlikely.

Rob

* Yeah, I'm glossing over neutrons. I'm also glossing over the possibility of
storing more than one bit per electron and other quauntum strangeness. I
have no idea how you'd _build_ one of these suckers. Nobody does yet.
They're working on it...
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