If you haven’t heard about Christopher Nolan’s ‘Inception’, you must be living in your own dream land. This was probably the most hyped up movie after ‘Avatar’ and definitely much more discussed than ‘Avatar’. Just in case you are one of those who hasn’t seen or heard about ‘Inception’, here is a gist of that movie. The movie plays as a dream in a dream in a dream format. There is a debate about whether the dream level is 5 or 6 but we will not go there. The premise of the movie is that there are certain ‘dream thieves’ who can penetrate anyone’s dream and can plant an idea. On waking up the person thinks it is his own idea. This is ‘Inception’.
Fans of Christopher Nolan make take issues with the title of this blog post. How is it that I am so casually saying that the ideas presented in ‘Inception’ are no brainer for Storage folks (and Virtualization folks) as well? Wasn’t Nolan’s movie one of the more complicated ones in recent times? Can I offer some proof to support my assertion? Well, here you go guys and pardon any bad puns along the way.
First, lets take the Virtualization angle. And let us take a simple case. We have an hypervisor on which an operating system runs. This is like the first level dream state. As I was trying to practice something on VMware ESX but did not have the hardware, I ran across an article which says that ESX can be loaded in a VMware Workstation!!! Now check this out: You first load the operating system, say some Windows OS, on top of it you load VMware Workstation. In this workstation, you load VMware ESX. On top of this hypervisor you can load your operating system. This could again be Windows!!! Unlike Nolan’s linear dream, we are in a circular dream four levels deep!! And if you want to add to the complexity, you can run a virtual appliance inside this Windows OS, which runs on the hypervisor, which is loaded on top of VMware workstation, which is loaded on Windows OS!!!! There you go. And according to the article I read, this is supposed to be a valid use case for testing and training!!! (Of course no one would want to use it in production.)
Let’s now shift to the Storage world and this dream in a dream becomes very commonplace. First, lets take the most basic unit, the LUN. This itself is a virtual entity which is carved out of multiple disks (configured as some RAID). Sometimes you may combine these LUNs to form a Meta LUN or you can present multiple LUNs to the server, which can combine them using Volume Manager. These combined LUNs can then then be split up again and assigned as single disks!! If you have a virtualization equipment in the network, that adds to the fun. You can have HDS USP or IBM SVC or NetApp N Series, for example, and these will take LUNs from heterogeneous storage, combine them, split them and present the modified LUNs to the server. Again a case of dream within a dream within a dream. These are not some theoretical use cases but rather daily use cases.
When you combine Virtualization with Storage, the whole thing goes haywire. You can have your basic LUNs on your arrays, these can be presented to a virtualization like USP, which can combine multiple LUNs and present it to the hypervisor for its datastore. The Hypervisor in turn uses this Datastore LUNs, carves up smaller disks from it and then presents it to the operating systems running on the hypervisor. Assume one of these Virtual Machines is running a virtual appliance, then the disks assigned to the operating system is further divided and a small portion is presented as a disk to the virtual appliance!! If you try explaining this to Nolan I am sure he will stop making movies with flashbacks or dreambacks and stick to linear storytelling!!
You can also argue that when the dream is on, the underlying reality may change and you may wake up at a different than when the dream started. That can happen here as well. Many of the virtualizing equipments like USP or EMC’s Rainfinity will move your LUN from one physical storage to another one without the user realizing that the underlying reality has changed. In short, Virtualization and Storage work most efficiently when the user is in a dream state and has no clue about the actual reality!!!
But… you say, Nolan’s movie was about sowing an idea. What idea is being sowed by Server and Storage Virtualization. According to me, it is the idea called ‘Cloud’. As in ‘Inception’, someone has managed to sow the idea so deep that every vendor thinks it is his / her own idea !!! Will ‘Cloud’ work like a dream or is it just a dream. I cannot answer yet as I am not sure if I am in a dream or not!! The protagonist Cobb explains in the movie, “You never know the beginning of a dream”. Since I am yet to find out the beginning of the ‘Cloud’ trend, I am unsure of myself!!! So, as far as the ‘Cloud’ is concerned, the totem is still spinning. In a few years we will know if the spinning stops. Till then….