Question $1$

$($Marks: $40)$

Review the following case study about Netflix, then answer the questions that follow.

Netflix is the world's leading internet television network, with more than $200$ million members in more than $190$ countries enjoying $125$ million hours of TV shows and movies each day. Netflix entertains the world, providing a wide variety of TV shows, movies, and documentaries to hundreds of millions of members across the globe in over $30$ languages. Users can stream Netflix shows and movies from anywhere in the world, including on the web, on tablets, or on mobile devices such as iPhones.

In its first incarnation, Netflix simply provided a better way to rent DVDs$.$ Going head$-$to$-$head with the then giant Blockbuster Video, a company that charged high late fees for DVD returns, Netflix allowed its customers to rent DVDs by mail with no late fees! Although the Netflix model didn't offer the instant gratification of taking home a DVD from a local store, it was simpler to rent from Netflix, and customers preferred the affordability Netflix offered. In this way, Netflix had seriously disrupted Blockbuster's business.

The subsequent introduction of Netflix's subscription streaming service also seriously disrupted major television networks such as ABC, CBS$,$ and NBC$.$ Until a few years ago, viewers could only watch TV shows on their television sets. As a result, TV moguls ABC, CBS$,$ and NBC were able to charge high advertisement rates and high subscription rates. When Netflix came on the scene, traditional TV broadcasting companies had to completely reshape how they delivered their offerings. In doing so$,$ their business operations were significantly disrupted. They no longer had the bulk of the market, their advertisement revenues dropped substantially, and their costs have increased to provide Webcasting services such as video$-$on$-$demand and Web delivery of content. However, Netflix didn't stop at disrupting other competitors$-$it went on to disrupt itself!

With the entry of more and more digital Webcast services such as HULU, ROKU, Sling TV$,$ Amazon Prime Video and Netflix were facing increasingly stiff competition. To survive and prosper, Netflix separated its first$-$run movie rental offerings from its Web streaming services and runs two business models simultaneously. In its latest incarnation, Netflix is focusing on edging out its competition with original programming. At the $2018$ Emmy Awards, Netflix had more Emmy nominations than premium cable giant HBO and took home $23$ prestigious awards! In creating a

new market, Netflix has avoided being displaced by its competitors and is one of the rare companies that has successfully disrupted itself.

Our journey to the cloud at Netflix began in August of $2008,$ when we experienced a major database corruption and for three days could not ship DVDs to our members. That is when we realised that we had to move away from vertically scaled single points of failure, like relational databases in our datacentre, towards highly reliable, horizontally scalable, distributed systems in the cloud. Circa late $2008,$ Netflix had a single data centre. This single data centre raised a few concerns. As a single point of failure $($a$.$k$.$a$.$ SPOF$),$ it represented a liability $-$ data centre outages meant interruptions to service and negative customer impact.

Additionally, with growth in both streaming adoption and subscription levels, Netflix would soon outgrow this data centre $--$ we foresaw an imminent need for more power, better cooling, more space, and more hardware. In the Netflix data centre, we primarily used Oracle to persist data. In parts of the movie recommendation infrastructure, we used MySQL$.$ Both are relational databases. In our data centre, we do not currently use key$-$value stores for persistent storage. In order to move data to SimpleDB and S$3,$ we needed to build a data replication system to replicate changes between our data centre and AWS, transforming the data model along the way.

We chose Amazon Web Services $($AWS$)$ as our cloud provider because it provided us with the greatest scale and the broadest set of services and features. The majority of our systems, including all customer$-$facing services, had been migrated to the cloud prior to $2015.$ Since then, we've been taking the time necessary to figure out a secure and durable cloud path for our billing infrastructure as well as all aspects of our customer and employee data management. We are happy to report that in early January, $2016,$ after seven years of diligent effort, we have finally completed our cloud migration and shut down the last remaining data centre bits used by our streaming service!

Moving to the cloud has brought Netflix a number of benefits. We have eight times as many streaming members than we did in $2008,$ and they are much more engaged, with overall viewing growing by three orders of magnitude in eight years. The Netflix product itself has continued to evolve rapidly, incorporating many new resource$-$hungry fea