On 07/11/2012 12:24 PM, Justin Stringfellow wrote:
>> Suppose you find a weakness in a specific hash algorithm; you use this
>> to create hash collisions and now imagined you store the hash collisions
>> in a zfs dataset with dedup enabled using the same hash algorithm.....
> Sorry, but isn't this what dedup=verify solves? I don't see the problem here.
> Maybe all that's needed is a comment in the manpage saying hash algorithms
> aren't perfect.
It does solve it, but at a cost to normal operation. Every write gets
turned into a read. Assuming a big enough and reasonably busy dataset,
this leads to tremendous write amplification.
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