[Info-vax] HPVM, OpenVMS Clustering and Volume Shadowing

[Jeremy Begg]

Hi Dave,

I have no direct experience of HPVM but I do recall some comments about it 
at the recent OpenVMS TUDs here in Australia.

The main limitation of HPVM for OpenVMS is that the guest cannot access 
shared storage, i.e. any storage hardware presented to the guest by HPVM 
must be for the guest's exclusive use.

The guest can however use MSCP to make the "exclusive" storage available to 
other nodes or to access storage served by other nodes.

Essentially you should regard OpenVMS in HPVM as a "V1.0" product for 
testing and evaluation purposes; it's not yet ready for "production" 
environments.  It should be adequate to set up a test/dev environment for 
your application.

Regards,

	Jeremy Begg

Dave wrote:
>       We have been discussing locally, the idea of OpenVMS as a Guest
> on HPVM, however, I seem to recall reading, or hearing, that there are
> certain limitations/restrictions/issues associated with Volume
> Shadowing and clustering, when the OpenVMS nodes are guests within
> HPVM’s.      Can you refresh my memory, or reassure me that this is
> not the case.
> 
>       We are currently running a 4 node cluster (3 x bl860c’s running
> 8.3-1H1, and 1 DS10 running Alpha 8.3).     Data integrity is
> maintained by running Volume Shadowing and creating shadow sets with
> units presented from XP subsystems located in two separate data
> centers (5 mile separation).
> 
>       As a theoretical exercise, we are examining the idea of adding a
> 5th node to the cluster, where this new node would be a HPVM
> guest.      The main questions are,
> 
> 1.	If this 5th node is an OpenVMS guest instance on HPVM, will it be
> able to see, and mount the Cluster-wide shadow volumes, either
> directly, or via MSCP??
> 2.	Are there any special considerations that need to be taken into
> account on the Guest instance.
> 3.	Are there other considerations (regarding say, Clustering) which we
> need to be aware of??
> 
> If anyone any experience with this type of configuration and would be
> willing to share, I'd be grateful.
> 
> Thanks for any information you can provide.
> 
> Dave.