Software Defined Infrastructure
Well, we have come full circle with this string of subjects; about making sure you are ready for the cloud. We have talked security, storage, access, connectivity and feasibility to name a few.
Now, lets discuss SDI. What is SDI? It simply stands for “Software Defined Infrastructure”. Many people have their own versions of what that truly encompasses, but I take it at face value only. It is infrastructure built, configured and accessed through software only.
As an example, lets take a look at an OpenStack cloud. Many of you already know that OpenStack is an open source cloud management tool. It does more than that, but to find out, you should grab a copy and play with it.
So lets say we have a base installation for the cloud:
- We have COMPUTE nodes to house our virtual server instances
- We have INFRASTRUCTRE nodes to manage a make the functionality of the cloud work
- We also have a CONTROL/LOGGING node to keep track of the working of the cloud.
Now with this scenario, you would think that the INFRASTRUCTRE nodes create the SDI. But they in all honestly, they only contribute. The COMPUTE nodes create the virtual server instances. In a regular datacenter, servers are hardware, so therefore they are part of the overall infrastructure.
What about routers, switches and firewalls? They too are hardware in a standard datacenter, but are a virtual instance created in the cloud. You can even have Load Balancers created virtually in the cloud, or just use its functions from the command line. And of course, they are also hardware in a standard datacenter.
What about storage? In OpenStack, you have local storage connected to the compute nodes, called “ephemeral” storage. That means the storage gets unallocated and goes away when a virtual instance is deleted. There is also block storage, which is storage used specifically to create volumes for instances to use by themselves or to share. Either way, it is not deleted when the instances that are using them are. Block storage is just like your NFS or SAN devices that are also quite common in just about every datacenter.
Lets look at a typical SDI now that we know the players. This will be from the software side only. We are assuming that all hardware is installed correctly for the cloud to function in an appropriate way.
You create a virtual server instance (VM). You tell it to connect to a network so it can communicate with the internet: virtual LAN, virtual switch, connected to a virtual router, then connected to the internet companies physical router through the physical wires that tie your systems together.
You create a volume inside the virtual storage provider (there is normally a physical storage device connected to the cloud, but you use the cloud’s controls to make the volumes.
So, lets look at what you have:
- Virtual Server Instance (vCPU, RAM, Local Storage)
- Virtual Volume (Connected to Block Storage)
- Virtual LAN (Gets an IP address and Gateway from cloud management tool)
- Virtual Router (Connects Virtual LAN to Physical LAN)
- Virtual Firewall (Restricts access to and from Virtual Server Instance)
- Virtual Load Balancer (Makes sure that if you need Load Balancing technologies, it is there to provide the pools for functionality)
As you can see, it is the same as if it was all physical hardware, but virtual. That is the whole premise of SDI. I tell my clients “It’s just the same as a virtual datacenter. It has all the moving pieces except air condition and power cords”)
By Richard Thayer