Where do all the indexed data and collection data get stored ? is it in ram or harddisk?

in below screenshots you can see the size occupied by the index and size occupied by the collection.

  1. Are both index data and collection data loaded in RAM?
  2. if collection data is loaded into RAM and if any data in collection gets updated, then this updated data is updated in harddisk through journaling?

i created textIndex on name,email field, this resulted in the index sized getting doubled (as shown in below screenshot).
Are both the textIndex and normal index get stored in RAM?
i know the advantage of having data in ram.
i’m just wondering if creating new indexes are occupying more RAM memory, then may be i need to consider increasing RAM size.

Before creating text index on name,email fields , these are the storage size of index

After creating text index on name,email fields , these are the storage size of index