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There is a "read disturbance effect" on MLC flash that causes wear on reads. MLC flash gets multiple bits per cell using several voltage levels. MLC flash is a

by kabdib 16y ago

There is a "read disturbance effect" on MLC flash that causes wear on reads. MLC flash gets multiple bits per cell using several voltage levels. MLC flash is also around 5K erase cycles (and about the same number of reads until you need to do an erase-and-rewrite). Multiplied out and properly wear-leveled this is not a big deal. We might be seeing crappy wear leveling, or badly written firmware, or the need for more ECC bits (yes, MLC has these, and they are /not/ optional) than the EE types think they can get away with. I've been writing flash file systems since 1991. They're fun as hell to work with.

adbge 16y ago
> I've been writing flash file systems since 1991. They're fun as hell to work with. Could you recommend any good resources for someone new to file system technology that is interested in their inner-workings? Thanks!
- kabdib 16y ago
  Practical File System Design: http://www.letterp.com/~dbg/practical-file-system-design.pdf http://www.letterp.com/~dbg/practical-file-system-design.pdf NT File System Design (Rajeev Nagar) -- you can find this used. I believe his web site had a PDF copy for a while, sans pictures. My favorite book on transactions is Bernstein's Principles of Transaction Processing (may also be available as a PDF somewhere, from the author). Read the v6 Unix file system code. That will date me, but it's /simple/ and it works. You can move up from there. btrfs is neat. I haven't looked at the code.