[Info-vax] VMware

[Bob Gezelter]

On Tuesday, December 10, 2019 at 4:26:29 AM UTC-5, Ian Miller wrote:
> On Tuesday, December 10, 2019 at 3:22:51 AM UTC, Dave Froble wrote:
> > On 12/9/2019 7:42 PM, Arne Vajhøj wrote:
> > > On 12/9/2019 5:33 PM, clair.grant at vmssoftware.com wrote:
> > >> The big thing for the people I talk with is that VMS is different.
> > >> The HW cost is certainly a big factor but even more important is that
> > >> these people already run dozens, if not hundreds, of VMware guests.
> > >
> > > Or thousands.
> > >
> > > Or maybe even tens of thousands if they are big.
> > >
> > >> They want VMS to be in there, too, possibly in many guests. The
> > >> message is always the same, don't be different if you want to stay
> > >> around.
> > >
> > > Being different means extra cost.
> > >
> > > Arne
> > >
> > >
> > 
> > I've mostly been a firm believer in the two rules of dealing with customers:
> > 
> > 1) The customer is always right
> > 2) When the customer is wrong, refer to rule #1
> > 
> > So giving customers what they want is smart business.
> > 
> > But, I have to ask, how do they run all those instances.  It seems to me 
> > that it would be an operations nightmare.  I'm guessing they use SANs so 
> > backup would not be such an issue.  But other operations?
> > 
> > Guess I'm still lost in the 1980s ....
> > 
> > -- 
> > David Froble                       Tel: 724-529-0450
> > Dave Froble Enterprises, Inc.      E-Mail: davef at tsoft-inc.com
> > DFE Ultralights, Inc.
> > 170 Grimplin Road
> > Vanderbilt, PA  15486
> 
> Hi David, to run lots of VM systems requires massive automation otherwise they have to employ lots of sysadmins and that costs to much. With the automation you can create a VM with linux+oracle etc at the press of a button in a very short time. All the VMs are monitored automatically, some fixes for problems are applied automatically and so on. Running 10,000 systems in a data center with a few people is possible. 
> 
> It is a strange new industrial big scale world. I mostly still handcraft VMS clusters from the finest ingredients so am a niche craftsman sitting in a corner while the young folk play with the shiny new industrial automated sysadmin toys.

Ian,

Perhaps it is a more subtle point. It is not so much a new world, as a world with a broader spectrum of possible choices and wider set of alternatives.

In the Windows/Linux world, many applications presume that they are on a dedicated instance. Attempting to run multiple applications in a single instance results in collisions, e.g., port numbers, serializations. Resolving such problems can be complex and time-consuming and requires the cooperation and assistance of outsiders. Using dedicated instances somewhat nullifies the problem by giving each their own "playpen" to operate within, which removes the issue of how well applications co-exist. 

It is also possible to have similar problems with databases and other multi-client packages. Not everyone operates well in a shared namespace.

Testing is yet a third situation. Many times, I have needed to do an experiment with potential consequences. Better to do it on a disposable virtual instance (an approach I described in a blog article several years ago) than impact a longer lived instance. One starts with a disposable instance, and graduates to a less disposable environment after one has proven feasibility.

Similar arguments hold for training and proficiency. Crashing an inexpensive disposable instance is far less expensive than real hardware.

In production contexts, there are parallel arguments. However useful VM migration, it is not a functional replacement for OpenVMS clusters. VM migration allows controlled workload migration, in the event of an uncontrolled system failure, e.g. complete power-failure without warning or system destruction. migration will not have sufficient time to execute a migration. 

A wide range of possibilities. One size does not fit all and not all options are appropriate for any particular context.

- Bob Gezelter, http://www.rlgsc.com