Re: [9fans] Venti and the hash / public key in plan9

[uriel@cat-v.org]

> Lluís Batlle wrote:
>> 2006/2/6, Russ Cox <rsc@swtch.com>:
>>>> Hi...  I've been reading the papers about Venti.  There is an
>>>> explanation about the low probability of the repetition of a hash
>>>> string in a normal-sized nowadays hard disk.  Anyway I've don't
>>>> understood what does Venti do when a hash is found in the stored
>>>> blocks, and the contents of the blocks are different (the
>>>> low-probability case).  I imagine there is some code which does not
>>>> give a data-loss...  Can someone give a small explanation about that?
>>> It responds to the write RPC with an error.
>> So what should manage that error? The application? Maybe it try a
>> different write size?
>> In fact there should be another application layer between 9p and the
>> RPC for venti, isn't it? (which?)
> Isn't the probability of such hash collisions "pretty" low ?
> (lower than the probability of hardware errors passing through
> undetected )

I think I heard someone quote Rob as saying something like: "lower
than the probability that all the atoms in one half of the universe
would get up all at the same time and move to the other side of the
universe"

If someone knows the exact quote please email it to me.

uriel