Every time i'm studying and trying (really hard) to understand what these hackers write, i meet

   2037 /*
   2038  * ==========================================================================
   2039  * Error rank.  Error are ranked in the order 0, ENXIO, ECKSUM, EIO, other.
   2040  * An error of 0 indictes success.  ENXIO indicates whole-device failure,
   2041  * which may be transient (e.g. unplugged) or permament.  ECKSUM and EIO
   2042  * indicate errors that are specific to one I/O, and most likely permanent.
   2043  * Any other error is presumed to be worse because we weren't expecting it.
   2044  * ==========================================================================
   2045  */
I really like the block comment above... (i did need to put it here). ;-)
The OpenSolaris source code is like read a book, just because the quality of the comments! So we
mortals can (try) to understand it.