Public Cloud Deployment Tip #3. Measure Throughput
Now, as the application isn't just one atomic unit, you'll need to measure the throughput for each high-level transaction. You need to perform this calculation across all your business transactions to get an accurate result.
It is important to examine individual transactions to ensure every business facing part of your application is accounted for, he notes.
Calculate the RATU for each of your relevant business transactions and take the average. You can customize this process a bit by excluding some transactions or even by doing a weighted average based on the importance or volume of the business transaction.
Now run the same analysis (calculating the RATU) on your test environment in the cloud. To get accurate numbers, you should take a measurement over a long enough time to cover at least one full workload cycle, if not more. As a rule of thumb, use a month of data as that should cover most variations in the application's lifecycle.
You should now have two numbers:
- RATU for the old data center environment
- RATU for your cloud
Simply divide the first by the second to see what percentage more cloud units you'll need to achieve the same performance as your current environment.
Using Amazon's elastic cloud (EC2) for an example, Livshutz says, "Say you have an asset tracking application, and have 100 large computers in your data center running the application. You can also run a test in the cloud of this same application, on 20 large- size ec2 nodes."
Suppose you find out that the data center RATU is 10,000, while the RATU in the cloud is 1,000. Therefore: 10,000 divided by 1,000 = 10.
"This means you will need 10 times more cloud units than data center hardware units to achieve satisfactory throughput," he says. "Since you are testing on 100 datacenter machines, you will need 1000 'large' nodes if you want to achieve the same throughput when you migrate to the cloud. Make sure you have enough money for all those nodes before you start!"
You may be noticed that Livshutz's tips require not only an APM system but one that has analytics as well.
That's the key, says Livshutz. "Your APM solution needs to be built from the ground up for the challenges of cloud environments. If it's not, it won't be able to accomplish what you need -- and your cloud initiative will be stuck in neutral."