[Info-vax] How do I avoid a full disk shadow copy when I shutdown/boot a node back into the cluster?

[Ken Fairfield]

On Wednesday, April 4, 2012 12:03:32 PM UTC-7, Len Whitwer wrote:
> Hi All:
> 
> How do I avoid a full disk shadow copy when I shutdown/boot a node
> back into the cluster?
> 
> Have two rx3600's with a SAN on each running OVMS I64 ver 8.4 with
> clustering and Volume Shadowning.
> 
> When one node (Clustered) goes down and then comes back into the
> cluster a
> COMPLETE shodow copy action is initiated on there-join. This takes
> about 9 hours
> which is unacceptable. There has to be a way around this where only
> the files
> that have CHANGED get updated!!!!!

1) Be sure you've configured and enabled HBMM (Host-Based Mini-Merge) 
   on all your shadow volumes.

2) Be sure you've called the appropriate shutdown procedures for
   your various applications in SYSHUTDWN.COM.

Regarding (2), VMS will do its best to kill all processes on the
system before dismounting the shadow volumes, but there are a
variety of reasons it might no succeed.  It's up to the system
manager to invoke any and all application shutdown procedures 
(think databases for example) during system shutdown.

Regarding (1), the system disk is always subject to merge on
shutdown, even a normal/controlled shutdown.  With the move to
FibreChannel (from CI), volume merges are no longer done in the
storage controller.  Rather, as of v7.3-2 (or late v7.3-1 with
appropriate ECOs), HBMM uses the functionality initially developed
for mini-copy to keep track of modified blocks (groups of 127
blocks usually) that will need to be merged should the shadow
volume be dismounted abnormally.  Of course for this to work,
you need to be in a cluster and at least one cluster member 
must survive the reboot or crash of some other system.  The
surviving member will merge the volume(s).

    -Ken