SUMMARY: Data Access Exception

From: Sam Finn (
Date: Tue Nov 10 1992 - 20:57:57 CST

The almost universal response was to install a fresh bootblock using
installboot. We gave this a try, but it did not work and the failure
mode was identical to before. I will keep the net informed should we
find either a hardware or software solution to the problem.

Thanks to all who replied,

Sam Finn

Original message:

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>From sun-managers-relay Mon Nov 9 23:26:17 1992
Date: Mon, 9 Nov 92 16:16:27 CST
From: (Sam Finn)
Reply-To: (Sam Finn)
Followup-To: junk
Subject: Data Access Exception on boot
Content-Length: 1485
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We've got a problem with a standalone sparc 2 running 4.1.1. The
internal disk is the boot disk. The machine crashed over the weekend,
and now, on boot we get a "Data Access Exception" and the boot fails.
The error occurs in one of two places in the boot process. Most often
the exception occurs after reading the text portion of vmunix (ie,
after the first set of vmunix numbers come up, but before the
+XXXX+XXXXX numbers). About once in five times, the failure is
immediate: after the monitor indicates it is going to the disk for
vmunix, but before even the first set of numbers indicating vmunix is
being read.

We've toggled the power numerous times, with no success.

We've booted the machine over the network and mounted the boot disk,
checking it with fsck. We don't seem to have any problems with mounting
or accessing the boot disk, so (I believe) we've ruled out controller
or disk problems. We pass the memory self-checks ok, so the data access
exception doesn't appear to be referring to ram. We've made a new kernel
and installed it on the boot disk, but the machine still fails to boot
in the same manner as before.

At this point, I am without the proverbial clue. I am leaning toward a
hardware problem (where is another question); however, it strikes me as
odd that I can boot from the network and mount and access the disk
without problems.
Thanks in advance for whatever help you can offer,

Sam Finn
Physics and Astronomy
Northwestern University


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