I like "Architecture of a Database System" by Stonebraker, Hamilton, and Hellerstein (http://db.cs.berkeley.edu/papers/fntdb07-architecture.pdf) for an overview and then "Transaction Processing: Concepts and Techniques" by Gray and Reuter (https://www.amazon.com/Transaction-Processing-Concepts-Techn...) for the storage-side of things. Granted these are a little old (especially G&R) so extra thought must be given for modern hardware (memory, CPU performance, processor counts, network, disks, etc) as well as distributed processing, replication, and consensus.