Welcome!

@CloudExpo Authors: Yeshim Deniz, Elizabeth White, Pat Romanski, Liz McMillan, Aruna Ravichandran

Related Topics: @CloudExpo

@CloudExpo: Blog Feed Post

Evaluating Cloud Computing Uptime SLAs

How many of us evaluate the vendor's Service Level Agreement (SLA) before they decide to deploy workloads in the cloud?

Last week's Windows Azure Storage outage made me thinking how many of us evaluate the vendor's Service Level Agreement (SLA) before they decide to deploy workloads in the cloud. I bet many think about it only when it is too late.



Let's take Windows Azure SLA and see how we as consumers of the cloud services are protected in case of downtime. Before all though I would like to point out that it is in the nature of any service (public or private) to experience outage once in a while - think about power outages that we hear about or live through every winter. It is important to understand that this will happen and as users of cloud services we need to be prepared for it. In this post I will use Windows Azure as example not because their services are better or worse than the other cloud vendors but to illustrate how the SLAs impact us and how they differ from vendor to vendor.

Each SLA (or at least the ones that bigger cloud vendors offer) contains few main sections:

  • Definitions - defining the terms used in the document
  • Claims - describing how and under what terms one can submit a claim for incidents as well as how much you will be credited
  • Exclusions - describing in what cases the vendor is not liable for the outage
  • The actual SLAs - those can be two types:
    • Guaranteed performance characteristics of the service
    • Uptime for the service

Looking at Windows Azure SLAs web page the first thing you will notice is that there are different SLAs for each service. You don't need to read all of them unless you utilize all of the services the vendor offer. The main point here is that you need to read the SLAs for the services you use. If, for example you use Windows Azure Storage and Windows Azure Compute you will notice that the uptime for those differ by 0.05% (Compute has uptime guarantee of 99.95% while Storage has uptime guarantee of 99.90%). Although this number is negligible at first sight using an SLA calculator you will notice that the expected downtime for Storage is twice as much as the expected downtime for Compute. It is obvious that the closer the uptime is to 100% the better the service is.

The next thing that you need to keep in mind is the timeframe for which the uptime is calculated for. In the case of Windows Azure the uptime is guaranteed on a monthly basis (for both Storage and Compute). In comparison Amazon's EC2 has annual uptime guarantee. Monthly SLA guarantees are preferable because you will avoid the case where the service experiences severe outage in particular month and stays up the rest of the year. Just to illustrate the last point imagine that EC2 experiences outage of 3h in particular month and stays up for the next 11 months. This outage is less than the 99.95% guarantee or 4:22:47.99 hours acceptable downtime per year and you will not be eligible for credit for it. On the other side if the SLA guarantee is on a monthly basis you will be eligible for the maximum credit for it because it severely exceeds the 21 minutes acceptable downtime per month.

One note about the acceptable downtime. In reality hardware in cloud data-centers fails all the time, which may result in downtime for your particular service but will not impact other services or workloads. Such outages are normally covered by the exclusion clause of the SLA and are your own responsibility. You should follow the standard architectural practices for cloud application and always make your services redundant in order to avoid this. The acceptable downtime metric is calculated for outages that impact vast amount of services or customers. Surprisingly though nowhere in the SLAs is mentioned how many customers need to be impacted in order for the vendor to report the outage. It may happen that a rack of servers in the datacenter goes down and few tens of customers are impacted for some amount of time. If you are one of those do not expect to see official statement from the cloud vendor about the outage. As a rule of thumb if the outage doesn't show up in the news you may have hard time proving that you deserve credit.

The last thing to keep in mind when evaluating SLAs from big cloud providers is the Beta and trial services. It is simple - there are no SLAs for services released in Beta functionality. You are free to use them at your own risk but don't expect any guarantees for uptime from the vendor.

When the so called secondary cloud providers are concerned you need to be much more careful. Those providers (and there are a lot of them) build their services on top of the bigger cloud vendors and thus are very dependent on the uptimes from the big guys. Hence they don't publish standard SLAs but negotiate the contracts on customer-by-customer basis. Most of the time this is based on the size of business you create for them and you can rely on good terms if you are big customer. Of course they put a lot of effort in helping you design your application for redundancy and avoid the risk of executing the SLA because of primary vendor outage. In the opposite case where you are a single developer you may end up without any guarantees for uptime from smaller cloud vendors.

More Stories By Toddy Mladenov

Toddy Mladenov has more than 15 years experience in software development and technology consulting at companies like Microsoft, SAP and 3Com. Currently he is a CTO of Agitare Technologies, Inc. - a boutique consulting company that specializes in Cloud Computing and Big Data Solutions. Before Agitare Tech Toddy spent few years with PaaS startup Apprenda and more than six years working on Microsft's cloud computing platform Windows Azure, Windows Client and MSN/Windows Live. During his career at Microsoft he managed different aspects of the software development process for Windows Azure and Windows Services. He also evangelized Microsoft cloud services among open source communities like PHP and Java. In the past he developed enterprise software for German's software giant SAP and several startups in Europe, and managed the technical sales for 3Com in the Balkan region.

With his broad industry experience, international background and end-user point of view Toddy has an unique approach towards technology. He believes that technology should be develop to improve people's lives and is eager to share his knowledge in topics like cloud computing, mobile and web development.

Comments (0)

Share your thoughts on this story.

Add your comment
You must be signed in to add a comment. Sign-in | Register

In accordance with our Comment Policy, we encourage comments that are on topic, relevant and to-the-point. We will remove comments that include profanity, personal attacks, racial slurs, threats of violence, or other inappropriate material that violates our Terms and Conditions, and will block users who make repeated violations. We ask all readers to expect diversity of opinion and to treat one another with dignity and respect.


@CloudExpo Stories
SYS-CON Events announced today that TidalScale, a leading provider of systems and services, will exhibit at SYS-CON's 21st International Cloud Expo®, which will take place on Oct 31 - Nov 2, 2017, at the Santa Clara Convention Center in Santa Clara, CA. TidalScale has been involved in shaping the computing landscape. They've designed, developed and deployed some of the most important and successful systems and services in the history of the computing industry - internet, Ethernet, operating s...
SYS-CON Events announced today that MIRAI Inc. will exhibit at the Japan External Trade Organization (JETRO) Pavilion at SYS-CON's 21st International Cloud Expo®, which will take place on Oct 31 – Nov 2, 2017, at the Santa Clara Convention Center in Santa Clara, CA. MIRAI Inc. are IT consultants from the public sector whose mission is to solve social issues by technology and innovation and to create a meaningful future for people.
The session is centered around the tracing of systems on cloud using technologies like ebpf. The goal is to talk about what this technology is all about and what purpose it serves. In his session at 21st Cloud Expo, Shashank Jain, Development Architect at SAP, will touch upon concepts of observability in the cloud and also some of the challenges we have. Generally most cloud-based monitoring tools capture details at a very granular level. To troubleshoot problems this might not be good enough.
SYS-CON Events announced today that IBM has been named “Diamond Sponsor” of SYS-CON's 21st Cloud Expo, which will take place on October 31 through November 2nd 2017 at the Santa Clara Convention Center in Santa Clara, California.
The next XaaS is CICDaaS. Why? Because CICD saves developers a huge amount of time. CD is an especially great option for projects that require multiple and frequent contributions to be integrated. But… securing CICD best practices is an emerging, essential, yet little understood practice for DevOps teams and their Cloud Service Providers. The only way to get CICD to work in a highly secure environment takes collaboration, patience and persistence. Building CICD in the cloud requires rigorous ar...
Join IBM November 1 at 21st Cloud Expo at the Santa Clara Convention Center in Santa Clara, CA, and learn how IBM Watson can bring cognitive services and AI to intelligent, unmanned systems. Cognitive analysis impacts today’s systems with unparalleled ability that were previously available only to manned, back-end operations. Thanks to cloud processing, IBM Watson can bring cognitive services and AI to intelligent, unmanned systems. Imagine a robot vacuum that becomes your personal assistant tha...
SYS-CON Events announced today that TidalScale will exhibit at SYS-CON's 21st International Cloud Expo®, which will take place on Oct 31 – Nov 2, 2017, at the Santa Clara Convention Center in Santa Clara, CA. TidalScale is the leading provider of Software-Defined Servers that bring flexibility to modern data centers by right-sizing servers on the fly to fit any data set or workload. TidalScale’s award-winning inverse hypervisor technology combines multiple commodity servers (including their ass...
Data scientists must access high-performance computing resources across a wide-area network. To achieve cloud-based HPC visualization, researchers must transfer datasets and visualization results efficiently. HPC clusters now compute GPU-accelerated visualization in the cloud cluster. To efficiently display results remotely, a high-performance, low-latency protocol transfers the display from the cluster to a remote desktop. Further, tools to easily mount remote datasets and efficiently transfer...
As hybrid cloud becomes the de-facto standard mode of operation for most enterprises, new challenges arise on how to efficiently and economically share data across environments. In his session at 21st Cloud Expo, Dr. Allon Cohen, VP of Product at Elastifile, will explore new techniques and best practices that help enterprise IT benefit from the advantages of hybrid cloud environments by enabling data availability for both legacy enterprise and cloud-native mission critical applications. By rev...
Infoblox delivers Actionable Network Intelligence to enterprise, government, and service provider customers around the world. They are the industry leader in DNS, DHCP, and IP address management, the category known as DDI. We empower thousands of organizations to control and secure their networks from the core-enabling them to increase efficiency and visibility, improve customer service, and meet compliance requirements.
In his session at 21st Cloud Expo, Michael Burley, a Senior Business Development Executive in IT Services at NetApp, will describe how NetApp designed a three-year program of work to migrate 25PB of a major telco's enterprise data to a new STaaS platform, and then secured a long-term contract to manage and operate the platform. This significant program blended the best of NetApp’s solutions and services capabilities to enable this telco’s successful adoption of private cloud storage and launchi...
With major technology companies and startups seriously embracing Cloud strategies, now is the perfect time to attend 21st Cloud Expo October 31 - November 2, 2017, at the Santa Clara Convention Center, CA, and June 12-14, 2018, at the Javits Center in New York City, NY, and learn what is going on, contribute to the discussions, and ensure that your enterprise is on the right path to Digital Transformation.
SYS-CON Events announced today that N3N will exhibit at SYS-CON's @ThingsExpo, which will take place on Oct 31 – Nov 2, 2017, at the Santa Clara Convention Center in Santa Clara, CA. N3N’s solutions increase the effectiveness of operations and control centers, increase the value of IoT investments, and facilitate real-time operational decision making. N3N enables operations teams with a four dimensional digital “big board” that consolidates real-time live video feeds alongside IoT sensor data a...
Amazon is pursuing new markets and disrupting industries at an incredible pace. Almost every industry seems to be in its crosshairs. Companies and industries that once thought they were safe are now worried about being “Amazoned.”. The new watch word should be “Be afraid. Be very afraid.” In his session 21st Cloud Expo, Chris Kocher, a co-founder of Grey Heron, will address questions such as: What new areas is Amazon disrupting? How are they doing this? Where are they likely to go? What are th...
In his Opening Keynote at 21st Cloud Expo, John Considine, General Manager of IBM Cloud Infrastructure, will lead you through the exciting evolution of the cloud. He'll look at this major disruption from the perspective of technology, business models, and what this means for enterprises of all sizes. John Considine is General Manager of Cloud Infrastructure Services at IBM. In that role he is responsible for leading IBM’s public cloud infrastructure including strategy, development, and offering ...
In the fast-paced advances and popularity in cloud technology, one of the most critical factors revolves around concerns for security of your critical data. How to assure both your company and your customers they can confidently trust and utilize your cloud environment is most often top on the list. There is a method to evaluating and providing security that exceeds conventional modes of protecting data both within the cloud as well externally on mobile and other devices. With the public failure...
Digital transformation is changing the face of business. The IDC predicts that enterprises will commit to a massive new scale of digital transformation, to stake out leadership positions in the "digital transformation economy." Accordingly, attendees at the upcoming Cloud Expo | @ThingsExpo at the Santa Clara Convention Center in Santa Clara, CA, Oct 31-Nov 2, will find fresh new content in a new track called Enterprise Cloud & Digital Transformation.
SYS-CON Events announced today that NetApp has been named “Bronze Sponsor” of SYS-CON's 21st International Cloud Expo®, which will take place on Oct 31 – Nov 2, 2017, at the Santa Clara Convention Center in Santa Clara, CA. NetApp is the data authority for hybrid cloud. NetApp provides a full range of hybrid cloud data services that simplify management of applications and data across cloud and on-premises environments to accelerate digital transformation. Together with their partners, NetApp emp...
The dynamic nature of the cloud means that change is a constant when it comes to modern cloud-based infrastructure. Delivering modern applications to end users, therefore, is a constantly shifting challenge. Delivery automation helps IT Ops teams ensure that apps are providing an optimal end user experience over hybrid-cloud and multi-cloud environments, no matter what the current state of the infrastructure is. To employ a delivery automation strategy that reflects your business rules, making r...
Most technology leaders, contemporary and from the hardware era, are reshaping their businesses to do software. They hope to capture value from emerging technologies such as IoT, SDN, and AI. Ultimately, irrespective of the vertical, it is about deriving value from independent software applications participating in an ecosystem as one comprehensive solution. In his session at @ThingsExpo, Kausik Sridhar, founder and CTO of Pulzze Systems, will discuss how given the magnitude of today's applicati...