Enter the Public Cloud
The private cloud, through enhanced management processes and virtualization, brings a highly optimized on-premises solution. Ultimately, it still consists of resources that the organization owns and has to house year-round. As I mentioned earlier, CIOs don’t like writing checks for datacenters, no matter how optimal. All the optimization in the world cannot counter the fact that there are some scenarios where hosting on-premises is not efficient or even logical.
The public cloud represents services offered by an external party that can be accessed over the Internet. The services are not limited and can be purchased as you consume the service. This is a key difference from an on-premises infrastructure. With the public cloud, you only pay for the amount of service you consume when you use it. For example, I only pay for the amount of storage I am using at any moment in time; the charge does not include the potential amount of storage I may need in a few years’ time. I only pay for the virtual machines I need turned on right now; I can increase the number of virtual machines when I need them and only pay for those extra virtual machines while they are running.
Turn It Off!
In Azure, virtual machines are billed on a per-minute basis. If I run an 8-vCPU virtual machine for 12 hours each month, then I only pay the cost for 12 hours of runtime. Note that it does not matter how busy the VM is. You pay the same price whether the vCPUs in the VM are running at 100 percent or 1 percent processor utilization. It’s important to shut down and deprovision from the Azure fabric any virtual machines that are not required to avoid paying for resources you don’t need. (Deprovision just means the virtual machine no longer has resources reserved in the Azure fabric.) The virtual machine can be restarted when you need it again. At that point, resources are allocated in the fabric automatically; the VM will start as expected.
In addition to the essentially limitless capacity, this pay-as-you-go model is what sets the public cloud apart from on-premises solutions. Think back to organizations needing DR services. Using the public cloud ensures there are minimal costs for providing disaster recovery. During normal running, you only pay for the storage used for the replicated data and virtual environments. Only in the case of an actual disaster would you start the virtual machines in the public cloud. You stop paying for them when you can fail back to on-premises.
There are other types of charges associated with the public cloud. For example, Azure does not charge for ingress bandwidth (data sent into Azure – Microsoft is fully invested in letting you get as much data into Azure as possible), but there are charges for egress (outbound) data. There are different tiers of storage, some of which are geo-replicated, so your data in Azure is stored at two datacenters that may be hundreds of miles apart. I will cover the pricing in more detail later in the book, but the common theme is you pay only for what you use.
If most organizations’ IT requirements were analyzed, you would find many instances where resource requirements for a particular service are not flat. In fact, they vary greatly at different times of the day, week, month, or year. There are systems that perform end-of-month batch processing. These are idle all month, and then consume huge amounts of resources for one day at the end of the month. There are companies (think tax accountants) that are idle for most of the year but that are very busy for two months. There may be services that need huge amounts of resources for a few weeks every four years, like those that stream the Olympics. The list of possible examples is endless.
Super Bowl Sunday and the American Love of Pizza
I’ll be up front; I’m English and I don’t understand the American football game. I watched the 2006 Super Bowl. After five hours of two minutes of action, a five-minute advertising break, and a different set of players moving a couple of yards, it’ll be hard to get me to watch it again. Nonetheless, it’s popular in America. As Americans watch the Super Bowl, they like to eat pizza, and what’s interesting is the Super Bowl represents a perfect storm for pizza ordering peaks. During the Super Bowl halftime and quarter breaks, across the entire United States, with all four time zones in sync, people order pizza. These three spikes require 50 percent more compute power for ordering and processing than a typical Friday dinnertime, the normal high point for pizza ordering.
Most systems are built to handle the busiest time, so our pizza company would have to provision compute capacity of 50 percent more than would ever normally be needed just for Super Bowl Sunday. Remember that this is 50 percent more than the Friday dinnertime requirement, which itself is much higher than is needed any other time of the week. This would be a hugely expensive and wasteful exercise. Instead Azure is used.
During normal times, there could be 10 web instances and 10 application instances handling the website and processing. On Friday nights between 2 p.m. and midnight, this increases to 20 instances of each role. On Super Bowl Sunday between noon and 5 p.m., this increases to 30 instances of each role. Granted, I’m making up the numbers, but the key here is the additional instances only exist when needed, and therefore the customer is charged extra only when the additional resources are needed. This elasticity is key to public cloud services.
To be clear, I totally understand the eating pizza part!
The pizza scenario is a case of predictable bursting, where there is a known period of increased utilization. It is one of the scenarios that is perfect for cloud computing. Figure 1.3 shows the four main scenarios in which cloud computing is the clear right choice. Many other scenarios work great in the cloud, but these four are uniquely solved in an efficient way through the cloud. I know many companies that have moved or are moving many of their services to the public cloud. It’s cheaper than other solutions and offers great resiliency.
Figure 1.3 The key types of highly variable workloads that are a great fit for consumption-based pricing
In a fast-growing scenario, a particular service’s utilization is increasing rapidly. In this scenario, a traditional on-premises infrastructure may not be able to scale fast enough to keep up with demand. Leveraging the “infinite” scale of the public cloud removes the danger of not being able to keep up with demand.
Unpredictable bursting occurs when the exact timing of high usage cannot be planned. “On and Off” scenarios describe services that are needed at certain times but that are completely turned off at other times. This could be in the form of monthly batch processes where the processing runs for only 8 hours a month, or this could be a company such as a tax return accounting service that runs for 3 months out of the year.
Although these four scenarios are great for the public cloud, some are also a good fit for hybrid scenarios where the complete solution has a mix of on-premises and the public cloud. The baseline requirements could be handled on-premises, but the bursts expand out to use the public cloud capacity.
For startup organizations, there is a saying: “fail fast.” It’s not that the goal of the startup is to fail, but rather, if it is going to fail, then it’s better to fail fast. Less money is wasted when compared to a long, drawn-out failure. The public cloud is a great option for startups because it means very little up-front capital spent buying servers and datacenter space. Instead, the startup just has operating expenditures for services it actually uses. This is why startups like services such as Microsoft Office 365 for their messaging and collaboration. Not only do they not need infrastructure, they don’t need messaging administrators