Summary; Sync SCSI on the SS1

From: Ron McDaniels (
Date: Thu Jan 02 1992 - 18:33:13 CST

I asked:

>SunOS 4.1.1b installed on an SS1. Wren VII doesn't boot up synchronous. I
>seem to remember that there is some nonsense about synchronous SCSI getting
>turned-off during device probe on an SS1 to mask a 3.5" disk drive problem
>but I can't remember the specifics. The question is, how do I get an SS1/SUNOS
>4.1.1b combo to run the disk synchronous.
> [attempt at humor deleted]

I got quite a few responses on this question (no corrections of spelling and
only one flame about me not picking up the answer from the sun-managers FAQ :-)

Most cautioned me not use sync SCSI on an SS1 because of problems in the SCSI
design on that processor. One respondent noted that the problem was
corrected in later versions of the SS1 and has been running with sync SCSI
enabled for almost a year. All (save one - the individual that flamed me) that
sent me a patch, agreed that the word kernel variable esp_ss1_esp0sync should
be set to 1 to make the SS1 use sync SCSI transfers. One person suggested the
patch be applied with the following line (as root) and the system rebooted:

        echo 'esp_ss1_esp0sync?W 1' | adb -w /vmunix

Although I was repeatedly warned that use of sync SCSI on the SS1 would result
in disc operations being retried (with a resulting loss of disc performance),
no one said that grossly unpleasant things would happen (corrupted disc files,
growth of hair on the palms of the hands, etc.), so I think that I will try it.

Many thanks to the following individuals:

Ron McDaniels
Science Horizons

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