Cloud Service Outage
If you are using one of the major CSPs (cloud service providers) you may already be used to major service outages. Amazon EC2, Rackspace, Google Apps and Microsoft Azure have all had their fair share of outages in the past 18 months, and some of them have been huge failures (Amazon’s April 2011 outage lasted 47 hours for some customers), which have brought down sites such as Reddit. However, companies such as Netflix have been able to survive the outages well. In this post, I will cover details on how you can effectively manage a service outage by taking note of best practices from Netflix and other companies that have successfully weathered the storm.
Create a disaster management fire-drill
Fire drills should be an essential part of cloud management. Once a month, have a fire drill to simulate failures in different parts of the system to see how your systems hold up in case of failures. This includes preparing your PR and customer service personnel, instituting quality control processes and executing an executive-level contingency plan to prevent panic from gripping the company.
Have all your data backed up securely
Periodically back up data and store it away from your primary CSP. For example, you could have an Amazon S3 instance to back up your Rackspace cloud installation. This will mitigate against a single point of failure.
Keep another service provider ready
Have another CSP ready to run an instance of your server at short notice, if needed. Even if it doesn’t provide full features for the site, this plan B should provide a minimum working subset. (In an email application, for instance, the service must allow you to send and receive email, even if contracts and archive access is not restored.)
Create stateless systems
One of the lessons Netflix offered was to build stateless systems where possible. That means a new request from the client can be served by any of the available servers, even if the original server to which the client made the request is down. This requires very careful planning during development.
Work on graceful degradation
Your system has a graceful degradation when a certain percentage of failure causes only an equivalent percentage drop in performance instead of bringing down the whole system. To enable graceful degradation, you must detect failures quickly (set quick timeouts when the system recognizes a failure) and shut down all non-essential features of the system (to save precious resources for critical features).
Create a communication plan to keep customers in the loop
If there is an outage at your CSP, your customers will also be affected. Imagine you are running an online store and the outage has prevented you from shipping. Even if none of the previous disaster management steps worked, you could save some of the bad press by keeping the customers and other stakeholders regularly informed of the status. Identify proper communication channels and create a plan to keep all of them in the loop. This requires having a backup of customer contact data, writing FAQs and preparing your employees to handle questions appropriately.
Having a proper service outage plan is essential to the survival of your business in the long-term. It could save a lot of headaches, not to mention your brand value, when failures do happen.
By Balaji Viswanathan