paulgorman.org

Thu 25 Jul 2019 09:15:57 AM EDT Slept from ten-thirty to four, then fitfully from five to seven. High of eighty-six and sunny today. A pretty woman said hello to me this morning, and, after a few beats, "have a good day!" I dunno, it was nice. (I think she's one of my neighbors who's lived a building over for a few months — the Asian with the cute dog.) Work: - Ask Julie about Lori's laptop Done. - Make software matrix Twenty-five-minute walk at lunch. Hot. Saw a dragonfly. https://www.reddit.com/r/homelab/comments/chjrve/how_parity_works_in_raid_in_plain_english_or_how/ > It turns out that XOR has an almost spooky-magical property to it. As long as you have three values, somebody can completely remove one of those values from the equation, and you can still go back in time and figure out what that value was! > > 0 XOR 1 XOR 1 = > > What do you get? The answer should be 0. This is your parity value. It's important, so, hang onto it. > > Now, randomly pick one of those three values in the equation, and pretend it has been destroyed. Died in a fire. Destroyed by monkeys. For the sake of the explanation, lets say the flaming monkeys destroy the middle value: > > 0 XOR ??? XOR 1 > > Believe it or not, we can actually figure out what that missing value was, by plugging in our parity value in its place, and re-running the calculation! So, lets try it.. > > 0 XOR 0 XOR 1 = .... > > You should get 1 as a result.. The number those damn flaming monkeys destroyed! > > This XOR magic trick works _regardless of how many values you have in the equation_: > > 1 XOR 1 XOR 0 XOR 1 XOR 0 XOR 0 XOR 1 XOR 0 = 0, right? > > Congratulations. You just repaired an 8-spindle RAID3, where each hard drive holds one bit of information. This trick works regardless of the number of bits, and regardless of the number of values, provided there are always at least three values to work with. Home: - Read at least the summaries from the Mueller report Pre-ordered the Criterion box set Godzilla: The Showa-Era Films, 1954–1975. https://www.reddit.com/r/AskHistorians/comments/chkpq2/why_does_it_seem_like_mosquitoes_are_not/ > But the only (more or less) mythological source I can think of in which something like a mosquito figures prominently is the poem "Culex," attributed to the great Roman poet Virgil. > > The eponymous culex is a "tiny nurseling of the moisture," but probably a gnat rather than a mosquito. It wakes a shepherd by biting him on the eyelid, and so saves him from a poisonous snake. The ungrateful shepherd squashes his savior. That night, however, he is visited by the ghost of the gnat, which criticizes him at length. A small sample: > > > Alas! how gratitude has gone aside > > From kindly service, when I from the very door > > Of death did give thee back to those above! > > O where are piety's rewards and where > > Its honors? (331-5) > > The dead bug continues in this vein for some time, describing the underworld and its denizens. At last it concludes, rather plaintively: > > > Away I'm going, never to return: > > Do thou, rejoicing, tend the pastures green > > And woods of fount and groves. (571-3) > > The shepherd wakes; and the following day he builds a nice little memorial for the gnat: > > > ...and with a plenteous mound > > Of earth a tomb arose in circle shaped. > > Around it placing stone of marble smooth, > > He plants it, mindful of his constant care. (590-2) Servings: grains 3/6, fruit 2/4, vegetables 4/4, dairy 1/2, meat 4/3, nuts 0/0.5 Brunch: left-over omelet half, banana, cucumber, coffee Lunch: omelet, apple, tomato Afternoon snack: coffee Dinner: Thai 103/65