Re: Virtual Databases

From: Jonathan Lewis <jonathan_at_jlcomp.demon.co.uk>
Date: Fri, 17 May 2013 11:01:09 +0100
Message-ID: <FbydncRLH5hLYgjMnZ2dnUVZ8qidnZ2d_at_bt.com>

"Mladen Gogala" <gogala.mladen_at_gmail.com> wrote in message news:pan.2013.05.15.19.05.19_at_gmail.com...

|

| What the heck are "virtual databases"? I consider a database real, for as
| long as I have to pay the real money for the instance(s) managing it. As
| soon as Oracle allows me to pay them with the Monopoly money, I will
| accept the term "virtual database". The term "virtual" is the marketing
| buzzword of the day, similar to the prefix "e-" from the late 90's.

Taking a simplistic view-point,

    a virtual network is a self-contained environment that emulates a network by using a portion of the resources made available by a real network

    a virtual machine is a self-contained environment that emulates a machine by using a portion of the resources made available by a real machine
hence

    a virtual database is a self-contained environment that emulates a database by using a portion of the resources made available by a real database

This seems to fit the interpretation used by Delphix, EMC, and other players in the market. The most significant difference in interpretation is that all of the suppliers require the physical resources of the underlying database to exist (viz: be "in use" somewhere); whereas a virtual machine or virtual network works only if the real resource is not otherwise in use As a side effect, the most significant benefit of the virtual database comes into play only when you have multiple virtual databases sitting on top of a single real database to get "N databases for the resources of one."

You might want to reconsider your use of the terms database and instance, by the way. Generally people pay a licence to run the software on a machine and you can have as many databases and instances on a machine as you like: so every instance after the first one is free, as is every database after the first database. Of course, they can't be called "virtual" because they would be using the full resources required for a database or instance.

Regards

Jonathan Lewis
http://jonathanlewis.wordpress.com/all-postings

Author: Oracle Core (Apress 2011)
http://www.apress.com/9781430239543 Received on Fri May 17 2013 - 12:01:09 CEST