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The Question is:
I have two vax 4000 705a in a cluster. I would like to use two others I have
for hardware failover
this is a dssi cluster and I connected all four
systems together and set the bootflags so the
replacement systems boot properly. when booting the old system works fine and
the new system boots half way and hangs when I try to boot it. I know I can
only boot one of them at a time because the boot from the same system segment.
HELP
The Answer is :
You cannot have the same host name and the same SCSSYTEMID host address
active in the same cluster at the same time -- and these values are
paired, so the entire cluster must be rebooted if either the SCS node
name or the SCS system ID (but not both) changes.
Bootstrapping this configuration should involve great care as well, as
cluster configurations with invalid VOTES and/or invalid (or creative)
EXPECTED_VOTES settings can trigger user data corruptions. (For details
on correctly setting the VOTES and EXPECTED_VOTES parameters, please
see the OpenVMS FAQ.)
If you endeavour to have two nodes booting from one root, this should
work -- assuming that the hardware configurations of the pairs are
sufficiently similar of course, and assuming that one of the two nodes
in the pair is always and reliably down. That written, the OpenVMS
Wizard would tend to use a cluster alias and would tend to keep all
four nodes active, each with a unique host name and SCS host address.
This tends to reduce the exposure to operator error, of course, and
this allows all four hosts to be continuously tested through normal
operation.
You can turn on procedure verification and determine where the hang
occurs, of course -- assuming the system has gotten that far. (With
no details on when the hang occurs, no specific answer is possible.)
The OpenVMS Wizard would also look to the exposure involved in the
operator input -- human error is a common source of problems -- and
the exposure to hardware-level failures in the storage area. DSSI
is an old (and slow) storage technology, and the hardware involved
in most DSSI configurations is aging and becoming coorespondingly
more prone to hardware failures.
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