Cloud Outages

Last week Amazon's cloud-based infrastructure went down hard, knocking Netflix offline on what should have been one of its most heavily trafficked days of the year, starting Christmas Eve and running well into Christmas Day. This week it's Microsoft's turn to suffer a severe cloud outage. At 3:16 PM on December 28, Microsoft reported that its Azure Storage service for the South Central US region was experiencing "partial availability." In an update a few hours later on its service dashboard, the company noted that the outage was affecting its worldwide Management Portal. I'm not aware of any cloud-based service that offers a 100% uptime guarantee, because such a promise is impossible to keep. If you can afford redundant storage in multiple zones, that's a good alternative, but that option is too expensive for anything but mission-critical services. As more and more services move to the cloud, this sort of outage is inevitable (but hopefully rare). And on the part of customers, responding to it with equanimity and professionalism is essential.

Software as a Service

In the SaaS model, cloud providers install and operate application software in the cloud and cloud users access the software from cloud clients. The cloud users do not manage the cloud infrastructure and platform on which the application is running. This eliminates the need to install and run the application on the cloud user's own computers which ultimately simplifies maintenance and support. What makes a cloud application different from other applications is its scalability. This can be achieved by cloning tasks onto multiple virtual machines at run-time to meet the changing work demand. Load balancers distribute the work over the set of virtual machines. This process is transparent to the cloud user who sees only a single access point. To accommodate a large number of cloud users, cloud applications can be multitenant, that is, any machine serves more than one cloud user organization. This is the type of service that supports IP telephony. It is common to refer to special types of cloud based application software with a similar naming convention: desktop as a service, business process as a service, test environment as a service, communication as a service.

Platform as a Service

In the PaaS model, cloud service providers deliver a computing platform typically including operating system, programming language execution environment, database, and web server. Application development uses this type of cloud service and runs the software solutions on the cloud platform without the cost and complexity of buying and managing the underlying hardware and software layers. With some PaaS offers, the underlying computer and storage resources scale automatically to match application demand such that cloud user does not have to allocate resources manually, which can save time and space. As a business owner, this is one of the best clouds to have in a small business. It will make life a lot easier and simpler not to have to worry about certain IT components of the business applications and communication applications. The PaaS has also saved me a lot of time as well as being very cost efficient.

Infrastructure as a Service

There are many different cloud services that improve the way a business runs and operates. One of the cloud services is providing the infrastructure. IaaS providers offer computers, virtual machines, and other resources. The virtual machines are run as guests by a hypervisor, such as Xen or KVM. Pools of hypervisors within the cloud operational support system support large numbers of virtual machines and the ability to scale services up and down according to customers' varying requirements such as web development and business application development. IaaS clouds often offer additional resources such as images in a virtual machine image library, raw and file-based storage, firewalls, load balancers, IP addresses, virtual local area networks, and software bundles. IaaS cloud providers supply these resources on demand from their large pools installed in data centers. For wide area connectivity, the Internet can be used or—in carrier clouds -- dedicated virtual private networks can be configured.