[Info-vax] automatic shadow copy?

[Michael Moroney]

IanD <iloveopenvms at gmail.com> writes:

>On Monday, March 23, 2015 at 9:43:52 AM UTC+11, Phillip Helbig (undress 
>to reply) wrote:
>> After upgrading to 8.4, I replaced a 4-GB member of the system-disk
>> shadow set (which I now have as a backup of the old system) with a 9-GB
>> disk.  (Soon, I will replace the 4-GB member and use DVE to increase the
>> size of the system disk.)  I put in the new disk, ran AUTOCONFIGURE, and
>> wanted to test it a bit before interactively adding it to the shadow
>> set.  However, within a few seconds it had somehow become the target of
>> a copy operation.  The copy operation looks OK and is doing what I
>> wanted.  Still, I am puzzled.  I have done this often before and have
>> never had the copy start automatically.

>> Has something changed in this area?

>Sorry but I don't know the answer to your question but I have a similar 
>question, so I hope you don't mind me piggybacking on your thread?  I'm 
>thinking the answer may possibly be related?

>I was under the impression that shadow members have to be specifically 
>added to the member set but when our system boots, the system disk shadow 
>member is automatically added and completes under a merge operation. 
>Obviously shadow system disk is ticked in sysgen etc

>I cannot find any reference to the shadow member disk anywhere in any 
>procedures we run so I'm guessing that this information is embedded 
>somewhere on the primary shadow member itself and that vms is 
>automagically adding in the second shadow disk member of the system disk 
>when it boot?

They system does an implicit $ MOUNT /SHADOW/INCLUDE on the system disk 
during startup.  The last membership is read (yes, it's on the drive) and
previous members are added back in.  If a drive is replaced using the same
name, Shadowing has no way of knowing that it's a different drive, other
than the lack of shadowing information on it will make it become a copy 
target.