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Presentation: Building Resilience in Production Migrations

Track: Production Readiness: Building Resilient Systems

Location: Ballroom A

Duration: 1:40pm - 2:30pm

Day of week: Wednesday

Level: Intermediate - Advanced

Persona: Architect, Backend Developer, Chaos/Resiliency/SRE, Developer

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What You’ll Learn

  1. Hear about resilience,  why it is important, what Netflix Billing Infrastructure is doing to avoid taking downtime.

  2. Learn about complex migrations that took place at Netflix, at scale and how we avoided downtime, while migrating customer’s billing state.

  3. Find out about some of the tools and technologies Netflix Engineering used for these migrations.


How do you migrate stateful systems with confidence? Especially when downtime is not an option? Netflix Billing Infrastructure needs to be up 24/7 to support 130+ million global customers. Billing services are the source of truth for a customer’s billing state which changes as customers apply gift cards, update their Method of Payment or are just charged every month. We want this experience to be seamless and accurate anytime, day or night, so our databases are constantly in action, with no possible downtime windows.   

We have succeeded in multiple major rewrites. In the first one, we migrated billions of rows from Oracle in our data center to MySQL AWS Cloud. Post that, we also rewrote Netflix Balance Service that manages gifts and promotions redeemed by customers. In the recent one, we rewrote our legacy invoice processing system and seamlessly transitioned from a MySQL solution to Cassandra. All these efforts involved different strategies that helped us achieve these with a flip of a switch and without anyone realizing that Netflix had been doing major overhauls of its Billing Infrastructure. We will share our migration stories and what helped us build resilience.

From this talk, attendees will learn:

  • Baseline Considerations to be thought through in migrations.
  • Variations and aspects of achieving zero downtime especially around state migration.
  • Tools and technologies that can be helpful.

What's the focus of the work that you do today?


I lead Billing Infrastructure Engineering at Netflix. We build the infrastructure that helps Netflix collect charges from its members. Part of that is to determine who should be charged and how much through our systems. We also hold all the gift codes and balances and track them. We also support major customer workflows. Our services participate in gift redemptions, Method of payment updates, cancellation requests etc.  We also do financial reporting.


What’s the motivation for this talk?


To get a bit of why resilience is important specifically for us. We believe that for systems like us, we do our best when we are not visible, when nobody notices. It's a topic very close to my heart, how to build resilient systems, how to not go down. Our infrastructure  shouldn't be the reason people cannot watch what they wanted to. The motivation of the talk is primarily to share some of the things that we have seen over the years. Since I joined Netflix we've done major overhaul and nobody has noticed that infrastructure has been shifting. These kind of  projects have a thought process which starts even before we start the project, how to manage the resiliency, not going down. We have some interesting stuff to share that other people can benefit from as well.


What are some of the specific things that will be in this talk?


There are two aspects when rewriting a system. One is not taking a downtime for the deployment of your code. And second is not taking a downtime to migrate the state from one store to other store. The talk is about how do you do these steps without being noticed. And we will share the stories of how we migrated at scale, the things we did, what helped us. How did we build confidence into our migration?,. How should you think about it when you want to not really impact customers, the different aspects of that.


What do you want someone who comes to your talks to walk away with?


My goal is for people to learn some of the tools and technologies that we have used, if they can find something similar in their world, and how possibly they can break down these bigger tasks into smaller buckets and be able to focus and solve it. Because every system that's running today around the world will need a rewrite at some point. I want people to walk away with confidence from our experience to solve a very common but complex problem in software. I'm hoping they'll learn some tips and tricks.

Speaker: Sangeeta Handa

Engineering Manager, Billing Infrastructure @Netflix

Sangeeta Handa leads Billing Infrastructure Engineering at Netflix. She is as much passionate about building scalable and resilient software as she is about leading highly engaged and impactful engineering teams. At Netflix, she has led many successful efforts including Netflix Billing Infrastructure migration from native data center to AWS, rewrite of multiple important services related to invoicing customers, gift card and promotions tracking for customers. Prior to Netflix, Sangeeta evangelized and led construction of Apple’s highly scalable financial reconciliation platform for mega-million transactions in credit card payments, iPhone & gift card transactions. Other than these she has also engineered many other systems, grounds up, that are still standing the test of time at Apple.

Find Sangeeta Handa at


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