I am using SSAS for reporting statistics on a big amount of data.
Recently I began learning best practices for tuning and I am interesting in how SSAS caches the data.
I have done my research and I've concluded that there are three types of cache that SSAS is using in order to avoid the direct disk IO hit.
- The Formula Engine Cache
- The Storage Engine Cache
- The Operating System Cache
So, the question is, when a cold query is taking place, will all the three levels store some data? If that is what is happening, is it possible that the same data is cached at different levels? If it is, then why is there such a high usage of cache, as this may consume almost entire RAM?
For example, is it possible that the FE Cache stores some of cellset or rowset data and at the same time the SE Cache stores some subparts of cellset or rowset data and also the OS Cache stores some data?