Infrastructure admin's dilemma: To do VM replication or to cluster?

Dan has some pointers:

Before such a decision can be made, it is very important to understand what are the organization’s goals. That is, what are they really trying to accomplish. Then the appropriate selection of products can follow. As the great sage, Yogi Berra once said, “If you don’t know where you’re going, you’ll end up somewhere else.”

Let’s us consider typical goals and see there it leads.

* Higher performance - In this scenario, the organization hopes to segment either the application or the underlying data allowing the work to be assigned to more machines. The desired result is reducing the time it takes for the work to be accomplished when compared to running the application on a single system. Quite often, a high performance computing/grid computing monitor is selected. While virtual machine software combined with the appropriate management software for virtualized environments and virtual machine replication technology could do the job, it is likely that the imposed overhead would result lower rather than higher performance.

Not only that, let me warn you, if you are a Virtualization Infrastructure consultant and have not worked with clustering solutions like openMosix, OSCAR Rocks, MPI etc and walk in to a heavy Linux/Unix/Windows environment, you might get your ass kicked by the Unix admins on this issues. And if you happen to run into a Oracle RAC DBA on your way out, you'd be humiliated royally! So my advice:

• Exactly what Dan says, check out what the organizations goal is, and this can be a huge thing to discuss.
• Check and do a pre-scan on the IT operations and applications stack: What can be clustered and what not
• See which applications can tolerate some seconds downtime, VMotion / Live Migration can go pretty fast BUT we still need to see really mission critical OLTP applications in productions, think of an Oracle 10g database doing several hundred thousand transactions per day, some go even crazy at per hour!
• Get the consensus from all ends, a CxO might have a different view than the IT OPS folks, I know its hard but you have to migle with the admins as well, never forget that!
• And please check out what clustering si all about, not knowing what it is can be hard when people with intelligent arguments will play you down.
  

Eventually virtualization will be a layer no one will look at anymore and then all the attention is going to be on..yes, you guessed itv right..APPLICATIONS!!!. We all have kind of forgotten than lately doing all kinds of cool things with the virtualization software.

So as a consultant, you would want to bank on a long term strategy and not a hypervisor which might be irrelevant tomorrow!

Check it out.