[Info-vax] booting on a single disk from a shadowset

[Tom Adams]

On Thursday, February 11, 2016 at 10:47:52 AM UTC-5, Jan-Erik Soderholm wrote:
> Den 2016-02-11 kl. 16:38, skrev Tom Adams:
> > I am looking into this because I was thinking about writing a system
> > recovery SOP for a failed computer that has a good disk. (I already have
> > a software-based recovery procedure, but it's more involved.  I was
> > thinking a hardware-based approach could be better in some
> > circumstances.)
> >
> > dsa0 has dka0 and dka100 as members with dka0 the master member.
> >
> > If I take down the system and disconnect dka0 and try to boot on dka100
> > then the system seems to hang during the boot (but maybe I did not give
> > it enough time).
> >
> > I am pretty sure that if I disconnected dka100 and left dka0 connected
> > then it would boot OK, but I can't recall trying it.
> >
> > The question is: Is there a quick way to get the system to book as a
> > shadow-set on dka100 when dka0 (the master member) is gone?
> >
> > That way, someone could just pull a good disk out of a failed ds10, pop
> > it into a spare ds10 and boot to recover the system.
> >
> 
> As far as I have seen, one can boot from either of the disks
> in the shadow-set. And also setup defboot_dev so that it points
> and will try both disks when (auto-) booting. That is part of
> the point with using HBVS in the first place.
> 
> I think you should try both ways and see if there is a differnce.

Not only did the boot halt for a minute or more, when I put things back together it booted with the shadow-set, it was fully intact, no merge.  That means that nothing was changed on the dka100.  The boot got as far as showing the VMS banner during the boot sequence.  I was thinking maybe it got stuck trying to write to a read-only disk.

But I will try on the other disk if other agree with you.

I was posting here in part because I did not want to do a lot of experiments that involved power up and down one of my DS10s. They are pretty old in dog years so I do my best to baby the power supplies and mother boards.