Monitoring tools need to work differently in the cloud than in the data center, and don't transfer easily from one setting to the other. "Monitoring tools don't like hundreds of instances to appear in a few minutes," he noted, although the cloud tends to work that way.
In the multi-tenant cloud, where servers are shared by different customers, monitoring tools also miss the fact that a customer's workload that keeps the server extra busy can delay a time-shared hand-off to another workload by a tick or two of the system clock. As this happens repeatedly, one customer is penalized by the activity of another, resulting in a 1%-2% loss of paid-for time.
When many fellow tenants on a server are doing this to a Netflix application, Netflix can detect the "stolen time." If it reaches 30% of its paid-for time, it kills its own job and restarts it on a fresh server, a practice that a later speaker highlighted as Netflix "throwing the server back to Amazon" rather than tolerating second-rate performance.
At the same time, capacity planning is easier in the cloud. If you are off on your projections, it only takes a short while to spin up more virtual servers in EC2. On the other hand, a customer like Netflix can complicate matters for the cloud supplier. Cockcroft drew another round of laughs when he noted that, "Amazon sometimes calls to ask us what we think we're going to need."
Netflix is a unique cloud customer. Its need to store petabytes of video products and stream large data sets to customers quickly, on demand, gives it a unique set of requirements that few are ever going to match. The fact that it's found Amazon EC2 a suitable replacement for its own data centers indicates the cloud will be able to take on some of the most strenuous enterprise tasks in the future.
Netflix likes concentrating on its core business and expanded delivery methods instead of building more data centers. It hopes growth continues to accelerate the way it has in recent months, and that Amazon EC2 will enable it to keep up. "We don't see why anyone would want to do it any other way now," Cockcroft concluded.