Re: NetBSD MBR boot / Error no operating system

[Robert Elz <kre%munnari.OZ.AU@localhost>]

    Date:        Fri, 20 Apr 2018 15:52:43 +0000 (UTC)
    From:        steve%prd.co.uk@localhost (Steve Blinkhorn)
    Message-ID:  <20180420155243.1AEBEB35FEF%viking.prd.co.uk@localhost>

  | But returning it to the server, it gives the message:
  |
  | NetBSD MBR boot
  | Error No operating system

This all comes from the MBR boot code (the 400 or so bytes that
follow the MBR partition table).   "No operating system" seems to
mean that the magic number of the bootable partition was not
correct.

That all was OK on the other system suggests that perhaps there's
a drive geometry mapping problem - to be as portable to ancient
systems as possible, the MBR boot code uses CHS addressing if
it believes that it should work (there's not much space there to allow
for fallbacks, and alternatives,...)

What does fdisk report about the MBR, and is that likely to be what
the system you want to boot from implements?

Also beware of sector size issues - drives in USB caddies sometimes
do not act the same way as when directly SATA connected (or so I
have read).

kre