It is important to understand that SolrCloud is horizontally scalable. However, each node needs to have a certain capacity. The amount of CPU, disk, and RAM required for each node in SolrCloud needs to be figured out for the efficient allocation of resources. Though no fixed number can be assigned to these parameters as each application is unique, each index within each application has a unique indexing pattern—the number of documents that need to be indexed per second, the size of the documents, and the fields, the tokenization and the storage parameters defined. Similarly, the search patterns would also differ across indexes belonging to different applications. The number of queries per second and the search parameters can be different. The amount of data retrieved from Solr and the faceting and grouping parameters play an important role in the handling of resources used during querying.

Therefore, it is difficult to assign numbers to the RAM, CPU, and...