[rescue] CDROM 512-byte boot questions

[Dave McGuire]

   This question wasn't directed at me, but I'll endorse it.  I'm 
currently running ZuluSCSI boards in several SPARCstations, two PDP-11s, 
and several VAXen. (PDP-11s and VAXen via SCSI host adapters that speak 
MSCP)

              -Dave

On 7/27/23 18:29, John Hudak via rescue wrote:
> Interesting information. TY. I am considering getting a ZuluSCSI board 
> since the SCSI2SD v5 is NLA.  Do you endorse it?
> Thanks
> J
> 
> 
> On Thu, Jul 27, 2023 at 4:01 PM vom513 via rescue <rescue at sunhelp.org 
> <mailto:rescue at sunhelp.org>> wrote:
> 
> 
>      > On Jul 27, 2023, at 12:54 PM, Jonathan Sturges via rescue
>     <rescue at sunhelp.org <mailto:rescue at sunhelp.org>> wrote:
>      >
>      > Hi,
>      > Nice summary, your understanding is correct.  Some small additions:
>      >
>      > *  Some OSes -- Solaris2, I'm fairly sure, maybe later SunOS? --
>     the SCSI drivers can issue the block size change command when the OS
>     is running (or are able to handle the 2k block size).
>      > *  OBP 3.x can issue the block change command too, IIRC; it's
>     really OPB 2.x and prior that have the hard requirement of a
>     512-byte block requirement for booting.
>      > *  Besides Plextor, most Panasonic, Toshiba and Pioneer drives
>     have jumperable block sizes.
> 
>     Thanks for the reply/confirmation.
> 
>     I did a bit more experimentation with the ZuluSCI and figured I’d
>     post my results to the list to benefit any future folks who might be
>     looking for this type of info.
> 
>     - CD6.iso : Zulu log shows it coming up in 2048-byte mode, but my
>     sun4c/m machines boot fine from it.  I don’t see a MODE SELECT in
>     the log - I guess the ZS is just operating in “soft” block mode and
>     honoring whatever request comes in ? (This is great by the way - not
>     looking a gift horse in the mouth)
> 
>     - CD6_512.iso : Block size specified as 512.  Works as expected.
> 
>     - CD6_2048.iso : Block size specified as 2048.  Machines will NOT boot.
> 
>     So it seems like _<BLOCKSIZE> is a “hard” setting.  Omitting this
>     seems to run the device in “soft” mode (hard/soft just my personal
>     terminology for this behavior).
>     _______________________________________________
>     rescue list - http://sunhelp.org/mailman/listinfo/rescue_sunhelp.org
>     <http://sunhelp.org/mailman/listinfo/rescue_sunhelp.org>
> 
> 
> _______________________________________________
> rescue list - http://sunhelp.org/mailman/listinfo/rescue_sunhelp.org

-- 
Dave McGuire, AK4HZ
New Kensington, PA