On 2015-10-21 07:51, Austin S Hemmelgarn wrote:
And I realize of course right after sending this that my other reply didn't get through because GMail refuses to send mail in plain text, no matter how hard I beat it over the head...On 2015-10-20 15:59, Austin S Hemmelgarn wrote:On 2015-10-20 15:20, Duncan wrote:Yes, there's some small but not infinitesimal chance the checksum may be wrong, but if there's two copies of the data and the checksum on one is wrong while the checksum on the other verifies... yes, there's still that small chance that the one that verifies is wrong too, but that it's any worse than the one that does not verify? /That's/ getting close to infinitesimal, or at least close enough for the purposes of a mailing- list claim without links to supporting evidence by someone who has already characterized it as not mathematically rigorous... and for me, personally. I'm not spending any serious time thinking about getting hit by lightening, either, tho by the same token I don't go out flying kites or waving long metal rods around in lightning storms, either.With a 32-bit checksum and a 4k block (the math is easier with smaller numbers), that's 4128 bits, which means that a random single bit error will have a approximately 0.24% chance of occurring in a given bit, which translates to an approximately 7.75% chance that it will occur in one of the checksum bits. For a 16k block it's smaller of course (around 1.8% I think, but that's just a guess), but it's still sufficiently statistically likely that it should be considered.As mentioned in my other reply to this, I did the math wrong (bit of a difference between kilobit and kilobyte)
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