[Info-vax] Current VMS engineering quality, was: Re: What's VMS up to these

[Paul Sture]

On Fri, 16 Mar 2012 02:17:28 -0700, John Wallace wrote:

> On Mar 16, 8:31 am, Paul Sture <p... at sture.ch> wrote:
>> On Fri, 16 Mar 2012 05:19:22 +0100, Michael Kraemer wrote:
>> > Paul Sture schrieb:
>>
>> >> There were a couple of other problems here.  When twenty odd
>> >> workstations were trying to reboot, when the network came back they
>> >> all did it more or less at once.
>>
>> > Yep, rather messy.
>> > Plus, when the network still had persistent/intermittent problems,
>> > the whole configuration remained dead in the water.
>>
>> We didn't usually have such a long outage.  Sometimes it hit the PCs
>> rather than the VMS systems, and in these cases we could carry on
>> working, but the PC only folks were out of luck.  With a bit of luck,
>> you could save any work in progress to your local PC disk, but that was
>> not always the case.
>>
>> >> Until I changed the workstations to use Dump Off System Disk (DOSD),
>> >> the server system disk would go into a full shadow merge (or was it
>> >> shadow copy?).  This caused further problems:
>>
>> >> a) the boot times were exceptionally long b) some part of DECnet
>> >> Phase V could time out and you'd have to reboot the workstation
>> >> later to recover from this
>>
>> > I don't know if this would have helped in the cases I experienced.
>> > But I'm rather sure the responsible VMS experts would have tried it,
>> > if possible. Too embarrassing, a VMS cluster unavailable for hours.
>>
>> It definitely helped us, but ISTR having more than one go at
>> implementing DOSD.  I finally acquired some definitive instructions amd
>> those worked fine.  I was the only one on our team to think about this
>> solution, so maybe there were many other system managers out there who
>> didn't know about it.
>>
>> Prior to getting DOSD working we would drop the system disk non-master
>> shadow set until the whole cluster was up.  Not an ideal workaround but
>> it did the job.
>>
> 
> The shadowed boot device vs DOSD scenario is an example of the need for
> real experience and expertise in cases like this. The rest of it mostly
> hopefully works out of the box, give or take, but there are sometimes
> details hiding in dark corners which will get you if you are unaware.

I must admit I used to devour DSN articles avidly when that was 
available, and picked up a great deal of information you couldn't acquire 
unless you had experienced a particular dark corner yourself.

-- 
Paul Sture