Forget for a minute you didn’t hear about ELSA and go through the post as it’s a good read about Hadoop’s pros and cons even if its main intent is to make you think “my ELSA is better than your Hadoop”:
The easiest alternative to using Hadoop for Big Data is to use multiple traditional databases and architect your read and write patterns such that the data in one database does not rely on the data in another. Once that is established, it is much easier than you’d think to write basic aggregation routines in languages you’re already invested in and familiar with. This means you need to think very critically about your app architecture before you throw more hardware at it.
This is the theory. For the practical part use something that works.
Original title and link: When to Use and Not to Use Hadoop: Hadoop vs ELSA ( ©myNoSQL)