What’s private? What’s public? What’s in-between? We’ve been talking quite a bit lately at Gartner about variations of isolation in a cloud computing architecture. It’s not black and white – it’s gray (aren’t all clouds?).
Private cloud computing requires that the enterprise have dedicated data centers and everything inside.
Public cloud computing assumes that the enterprise is using a service where everything is potentially shared with other users. Everything. Including transactions, data, analysis of the data – everything that took place or was stored as a part of the service (think Google search).
There are plenty of variations between the two – here’s a few:
- Perhaps you don’t want to share the transactions and analysis. You’re willing to use/share public data, you’re willing to share software – but how you use the software is your business.
- Or perhaps the data is yours. You will share a multitenant application and everything below it (think Salesforce.com).
- Or perhaps the you don’t want to share the application – you want your own dedicated copy, running on your own dedicated operating system, perhaps running in a virtual machine (typical Amazon EC2 deployment).
- Or, perhaps you want better isolation – you want your software to be the only thing running on your hardware at any one point in time. You may need more, you may need less, but when you acquire it it is all yours until you are done (typical horizontal scaling for web servers in the cloud).
- Or perhaps you want even more isolation – the hardware is reserved for you and you alone (think Exchange Online Dedicated).
And in all of this, management could be dedicated to just your stuff, or it could be shared. Management could even be running on dedicated hardware – or shared. And there are more variations.
A term starting to float out there in the industry is “virtual private clouds”. Reuven Cohen probably invented the term, but his use is different from some of the uses I’ve heard from vendors. Beware! It will be really important to understand what is truly “private” and what is truly “shared” when vendors start to use that term and many others to discuss what they’ve got. I can already hear the drumroll for more cloud computing terms being used in fifteen different ways – or is that thunder?