Ask HN: What are some good resources for learning about low level disk/file IO?

  * how to ensure data's been safely written (e.g. when to flush, fsync, what
    guarantees that gives, using WAL)
  * blocks sizes to read/write for different purposes, tradeoffs, etc.
  * considerations for writing to different media/filesystems (e.g. disk, ssd, NFS)
  * when to rely on OS disk cache vs. using own cache
  * when to use/not use mmap
  * performance considerations (e.g. multiple small files vs. few larger ones,
    concurrent readers/writers, locking, etc.)
  * OS specific considerations