Re: bad144 - how useful still? Because it's annoyingly ubiquitous.

[Thor Lancelot Simon <tls%panix.com@localhost>]

On Sun, May 31, 2026 at 10:16:39AM -0400, Jason Thorpe wrote:
> 
> > On May 31, 2026, at 10:10???AM, Jason Thorpe <thorpej%me.com@localhost> wrote:
> > 
> > 
> >> On May 31, 2026, at 7:07???AM, Thor Lancelot Simon <tls%panix.com@localhost> wrote:
> >> 
> >> The underlying hardware's often the same (CDC made the guts of plenty of
> >> DEC drives), SMD drives internally have no facility for sparing out sectors,
> >> and I wonder whether Sun did in fact do it.  However, I just Googled around
> >> for SunOS 3 source code and I see no evidence of a bad144 utility, though
> >> I did not dig through the kernel looking for driver support.
> > 
> > SunOS 3 certainly had a flag for "use DEC std 144" in the dk_info structure (<sun/dkio.h>).
> 
> ???and it certainly appears that the SunOS 3 ???xy??? driver uses it, including with big-endian fields, heh.

Huh.  I wonder how it got populated.  I'm vaguely remembering they might
have had a "format" utility or something.

Means moving a drive physically from a DEC system to a Sun VME system
would have lost the bad block table, right?  I remember seeing exactly
that done a few times with CDC drives that went from VAXen with Emulex
controllers to Sun replacements which I expect had Xylogics controllers.
I guess to do this safely must have required a low-level reformat by
something that wrote the bad144 data in the expected byte order.

-- 
Thor Lancelot Simon	                                     tls%panix.com@localhost
  "The liberties...lose much of their value whenever those who have greater
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