The technological terms “virtual” and “cloud” are becoming common. Industry press and sales copy frequently mention virtual computing, virtual servers, cloud computing and cloud servers. As a consumer of these services, you need to understand these terms at some level to help you determine if a given hosting provider or other vendor can actually deliver the full value of these services.
What Is Wrong With Good Old-Fashions Servers?
When the hardware that a server runs on needs to be replaced, it must be shut down. The IT staff installs the server operating system on the new hardware along with other software, then configures it to run smoothly on the hardware. This can take from hours to days, requiring skilled IT staff for the duration. Most of this can be done in advance for a planned upgrade, but for a hardware failure, IT personnel must get the server back up within a reasonable amount of time, sometimes up to a couple of days. With the adoption of the Internet, the definition of “reasonable” has shrunk to minutes and is headed for “instantaneous.”
What is Virtual?
In the computer field, the word “virtual” refers to something that appears to be a physical device but is really simulated with software. Software, called a virtual device, can be written to simulate the behavior of any mechanical or electronic device. The virtual device is not virtual reality where you can actually see the device working with your eyes, but a virtual device will interact with software just like a physical device would.
A Virtual Server Runs on a Virtual Machine
How does this help shorten the task of hardware changes? If you expand the virtual device idea to include all the hardware in a computer, you end up with a virtual machine. A virtual server is just all the server software installed on a virtual machine. The virtual machine is created by software known as a virtual machine supervisor program, sometimes called a hypervisor.
Once you have a virtual server, when you need to upgrade the hardware, you only need to copy the virtual server to the new hardware with a hypervisor installed, and you are ready to go. This requires far less staff time. You may also run more than one virtual machine simultaneously on the same hardware. This can save money on hardware when you need to run two servers that require different server operating systems. For example, you can have one physical machine, simultaneously running multiple virtual servers (ex. one Window Server, one Linux and one running a beta version of the next release of Windows Server).
Virtual Server Limitations
The virtual server enables you to reduce down time to a few minutes for hardware failures and upgrades. How do you get down to seconds or less? Virtual servers are great, but they still have limitations. For example, a virtual server is tied to a physical computer. Although you can now move a virtual server to new hardware quickly, the procedure still takes the intervention of IT personnel. Another potential weakness is that if there is a spike in the demand on one of the virtual servers, the performance of all of the virtual servers on that hardware can suffer.
A Cloud Server is Never Off-line
A cloud server is like a virtual server, except it is not restricted to run on one physical computer. The cloud consists of hundreds of physical machines, called nodes. Each node has its own processors and memory, and each can access any disk and run tasks for any cloud server. If you are browsing a site that is running on a cloud server, you will not notice anything different about it, except that the site is responsive, with no intermittently slow pages. Each task the virtual server performs, like serving a web page or running a database query, can run on whichever node has the least to do at that time.
This also means that failure of one of the physical nodes in the cloud has little effect overall. If the cloud has 500 nodes and one fails, the other 499 can take up the slack without stressing the system as a whole. Hardware upgrades are never needed for an individual cloud server, because as the demand for an individual cloud server grows, it will naturally begin to use more nodes. Although the cloud itself needs new nodes added and replaced, this is an on-going process that rarely, if ever, interferes with the availability of an individual cloud server.
No doubt, you noticed the progression in an increasing level of sophistication as these ideas were explained. It is hard to imagine what the next level would be beyond cloud servers. You are likely to see the cloud in an increasing variety of uses. Being able to seamlessly access the cloud to extend the power of your laptop, tablet or mobile device is probably not too far off for apps that require massive amounts of memory or processing power. However, if you see an obvious next level of sophistication beyond cloud computing, or have a killer application that would be uniquely enabled by the cloud, do not tell a soul, not even your mother. Then immediately do a search for “patent attorney.”