SQL Server buffer pool

An SQL Server buffer pool, also called an SQL Server buffer cache, is a place in system memory that is used for caching table and index data pages as they are modified or read from disk. 

The primary purpose of the SQL buffer pool is to reduce database file I/O and improve the response time for data retrieval. In SQL Server 2014, administrators can extend the buffer pool to a nonvolatile storage device such as a solid-state drive (SSD) or an SSD array. SQL Server writes only clean pages to the buffer extension in order to minimize the risk of data loss. By extending the buffer pool, administrators can realize performance gains for online transaction processing (OLTP) workloads, especially those that are read-intensive.