[HN Gopher] A disk is a bunch of bits (2023)
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       A disk is a bunch of bits (2023)
        
       Author : rrampage
       Score  : 13 points
       Date   : 2025-05-17 21:19 UTC (3 days ago)
        
 (HTM) web link (www.cyberdemon.org)
 (TXT) w3m dump (www.cyberdemon.org)
        
       | addaon wrote:
       | An okay overview of some high level context for on-disk storage,
       | but it's perhaps more useful to say that disk hardware (and
       | memory hardware) present an abstraction of a bunch of bits. Even
       | for DRAM, there isn't a one-to-one mapping between capacitors the
       | fab etches into the silicon and bits that your software can
       | access at a given physical address. At the lowest level,
       | defective rows are bypassed and remapped. At the next level up,
       | ECC means that a single bit can never be (reliably) pointed at on
       | its own -- instead, the data of, say, 64 bits is smeared across
       | 72 capacitors. For disks, this gets even worse, both because the
       | hardware itself is less reliable and because the slow speed
       | allows more and more tricks to be played. A bunch of bits get
       | mapped to a bunch of blocks, but blocks get remapped, bits within
       | blocks get error corrected, multiple bits are stored in a single
       | physical element, etc.
        
       | stevetron wrote:
       | A disk is circular.
        
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       (page generated 2025-05-20 23:00 UTC)