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

["\"Nils O. Selåsdal\"" <noselasd@asgaard.homelinux.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 )