Hard Lessons of Public Cloud: Designing for When AWS Goes Down
March 07, 2017

Eric Wright
Turbonomic

Share this

So, your site is down because AWS S3 went away. Too soon? It's never too soon to talk about why the responsibility for designing resilient infrastructure belongs in your camp. It's like when Smokey the Bear used to say that "only you can prevent forest fires." The difference is that it's Jeff Bezos saying it this time.

We have some real insight into what design for cloud resiliency really means thanks to a chat that I had recently.

Cloud Goes Down, so Design for It

There is no special text in the terms and conditions. These are hard facts. AWS designs its infrastructure to be as resilient as possible, but clearly tells you that you should design with the intention of surviving partial service outages. It isn't that AWS plans on being down a lot, but they have been hit by specific DDoS attacks, and also have had to reboot EC2 hosts in order to patch for security vulnerabilities.

At the time I was writing this, AWS S3 was fighting its way back to life in the US-east-1 Region. This means that there were multiple Availability Zones in the throes of recovery, and that potentially hundreds of thousands of web sites, and applications were experiencing issues retrieving objects from the widely used object storage platform.

So, how do we do this better? Let's ask someone who does design and see how the developers think about things. With that, I wanted to share a great discussion that I had with former Disney lead architect and current Principal Software Architect at Turbonomic, Steve Haines.

Q&A: Understanding the Developer's Reaction to the AWS Outage

EW: What does it mean to think about designing across regions inside the public cloud?

SH: Designing an application to run across multiple AWS regions is not a trivial task. While you can deploy stateless services or micro-services to multiple regions and then configure Route53 (Amazon's DNS Service) to point to Elastic Load Balancers (ELBs) in each region, that doesn't completely solve the problem.

First, it's crucial to consider the cost of redundancy. How many regions and how many availability zones (AZ) in each region do we want to deploy to? From historical outages, you're probably safe with two regions, but you do not want to keep a full copy of your application deployed in another region just for disaster recovery: you want to use it and distribute workloads across those regions!

For some use cases this will be easy, but for others you will need to design your application so that it is close to the resources it needs to access. If you design your application with failure in mind and to run in multiple regions then you can manage the cost because both regions will be running your workloads.

EW: That seems to be a bit of the cost of doing business for design and resiliency, but what is the impact below the presentation layers? It feels like that is the sort of "low hanging fruit" as we know it, but there is much more to the application architecture than that, right?

SH: Exactly! That leads to the next challenge: resources, such as databases and files. While AWS provides users multi-A to Z database replication free of charge for databases running behind RDS, users are still paying for storage, IOPS, etc. However, this model changes if a user wants to replicate across regions. For example, Oracle provides a product called GoldenGate for performing cross-region replication, which is a great tool but can significantly impact your IT budget.

Alternatively, you can consider one of Amazon's native offerings, Aurora, which supports cross- region replication out-of-the-box, but that needs to be a design decision you make when you're building or refactoring your application. And, if you store files in S3, be sure that you enable cross- region replication, it will cost you more, but it will ensure that files stored in one region will be available in the event of a regional outage.

EW: Sounds like we have already got some challenges in front of us with just porting our designs to cloud platforms, but when you're already leaning into the cloud as a first-class destination for your apps we have to already think about big outages. We do disaster recovery testing on-premises because that's something we can control. How do we do that type of testing out in the public cloud?

SH: Good question. It's important to remember that while designing an application to run in a cross-region capacity is one thing, having the confidence that it will work when you lose a region is another beast altogether!

This is where I'll defer to Netflix's practice of designing for failure and regularly testing failure scenarios. They have a "Simian Army" (https://github.com/Netflix/SimianArmy) that simulates various failure scenarios in production and ensures that everything continues to work. One of the members of the Simian Army is the Chaos Gorilla that regularly kills a region and ensures that Netflix continues to function, which is one of the reasons they were able to sustain the previous full region outage.

If you're serious about running across regions then you need to regularly validate that it works!

But maybe we should think bigger than cross-region – what if we could design across clouds for the ultimate protection?

EW: Thanks for the background and advice, Steve. Good food for thought for all of us in the IT industry. I'm sure there are a lot of people having this discussion in the coming weeks after the recent outage.

Eric Wright is Principal Solutions Engineer at Turbonomic.

Share this

The Latest

June 23, 2017

"Become the Automator, Not the Automated." While it's a simple enough phrase, it speaks directly to how today's organizations and IT teams must innovate to remain competitive. A critical aspect of innovation is acknowledging the digital transformation of businesses. The move to digitalization enables organizations to more effectively unlock the power of information technology (IT) to fuel and accelerate business innovation. It is a competitive weapon and a survival imperative ...

June 22, 2017

Executives in the US and Europe now place broad trust in Artificial Intelligence (AI) and machine learning systems, designed to protect organizations from more dynamic pernicious cyber threats, according to Radware's 2017 Executive Application & Network Security Survey ....

June 21, 2017

While IT service management (ITSM) has too often been viewed by the industry as an area of reactive management with fading process efficiencies and legacy concerns, a new study by Enterprise Management Associates (EMA) reveals that, in many organizations, ITSM is becoming a hub of innovation ...

June 20, 2017

Cloud is quickly becoming the new normal. The challenge for organizations is that increased cloud usage means increased complexity, often leading to a kind of infrastructure "blind spot." So how do companies break the blind spot and get back on track? ...

June 19, 2017

Hybrid IT is becoming a standard enterprise model, but there’s no single playbook to get there, according to a new report by Dimension Data entitled The Success Factors for Managing Hybrid IT ...

June 16, 2017

Any mobile app developer will tell you that one of the greatest challenges in monetizing their apps through video ads isn't finding the right demand or knowing when to run the videos; it's figuring out how to present video ads without slowing down their apps ...

June 15, 2017

40 percent of UK retail websites experience downtime during seasonal peaks, according to a recent study by Cogeco Peer 1 ...

June 14, 2017

Predictive analytics is a popular ITOA technology that you can leverage to improve your business by leaps and bounds. Predictive analytics analyzes relationships among various data points to predict behavioral trends, growth opportunities and risks, which can add critical value to your business. Here are a few questions to help you decide if predictive analytics is right for your business ...

June 13, 2017

Many organizations are at a tipping point, as new technology demands are set to outstrip the skills supply, according to a new Global Digital Transformation Skills Study by Brocade ...

June 12, 2017

Network capacity is the lifeblood of an enterprise — bandwidth enables business. Getting the most out of the network is a fine balancing act, so it's understandable that enterprises are always hungry for more bandwidth. Two out of three IT and network professionals expect bandwidth usage to increase by up to 50% by the end of 2017. However, bandwidth availability issues could become a thing of the past. We are on the cusp of a great surge of capacity as gigabit speed internet becomes a reality ...