In Chapter 2, Comprehensive Concepts of a Data Lake, you would have got a glimpse of Data Storage and Lambda Speed layer. The Data Storage layer’s responsibility is to persist the gathered data into a permanent place in our data lake. The Lambda Speed Layer’s responsibility is to index the data stored in Data Storage layer and create appropriate speed views. The following figure would refresh your memory and give you a good pictorial view of this layer:

Figure 01: Data Lake: Data Storage and Lambda Speed Layer

We have given enough details in a previous chapter on the Data Storage Layer so we don't want to repeat ourselves. The Lambda Speed layer stores the various speed views created from the data storage layer. Since it was just the previous chapter, your memory would also be quite fresh.