anchor.diff:  the whole data centre loses power at the same time, then it is possible that
   you could lose the last 5 seconds (or `sync_interval`) of data.
   
  -******************************************************
  +We are constantly monitoring the perfromance implications of better default
  +translog sync semantics, so the default might change as time passes and HW,
  +virtualization, and other aspects improve.
  +
  +******************************************************
positive.code: to the `sync_interval`.
  
  The `buffered` translog is written to disk when it reaches 64kB in size, or
  whenever an `fsync` is triggered by the `sync_interval`.
  
  .Why don't we `fsync` the translog after every write?
  ******************************************************
  
negative.code: 
  `index.translog.sync_interval`::
  
  How often the translog is ++fsync++ed to disk. Defaults to `5s`. Can be set to
  `0` to sync after each operation.
  
  `index.translog.fs.type`::
  
  