[mod.computers.vax] VMS Shadowing bug/gotcha

welch@UMass.BITNET (11/02/86)

Here's an interesting "gotcha" I just came across having to do with
VMS shadowing:

After installing the shadow key on our clustered CPUs we tried using
shadowing.  It worked only on out 8600 - DEC software support
checked things out and said everything looked fine.  After much
head scratching we realized the difference between our 8600 and
the other CPUs was the type of system disk.  The 8600 is on
a DU disk and the rest on RM05s.

As an experiment we booted another CPU off a spare DU disk and lo and
behold shadowing worked for that CPU, too.

So (at least for now) anyone planning to use shadowing should be warned
that for it to work you must boot from a DU (I suppose any DSA type
disk would work) to get the shadow driver to load instead of the
DUDRIVER.

Bitnet: Jhwelch@Amherst or
        Welch@Umass

				-Jonathan.