🚀 go-pugleaf

>Everybody seems to be missing the crucial fact about memory mapped files!
>
>They ONLY work for cases where the file size is < virtual address space!!!
>
>They are not a a generally useful solution which works over all possible
>implementations.  UNIX file I/O does work over all situations!

Anecdote: 
    The BSD kernel used to check the "seek pointer" of a file before
access, even on sequential files and special devices.  If the seek
pointer were negative, an error was returned.
    Gould built a device called an HS[CXD] (I can't remember the exact
name - similar to the so-called "Cray-Channel" (in fact, a modified
system was used for Cray connectivity).  Reasonably mongo I/O
throughput (even now).  Only took a few seconds for the seek pointer
to reach 2^(31) and turn negative -- at which point the device stopped
working.

Moral: UNIX file I/O may not work in all situations.

--
Andy Glew, aglew@uiuc.edu