The architecture of Couchbase Server includes a built-in caching layer. This caching layer acts as a central part of the server and provides very rapid reads and writes of data. Other database solutions read and write data from disk, which results in much slower performance. One alternative approach is to install and manage a caching layer as a separate component which will work with a database. This approach also has drawbacks because the burden of managing transfer of data between caching layer and database and the burden managing the caching layer results in significant custom code and effort.
In contrast Couchbase Server automatically manages the caching layer and coordinates with disk space to ensure that enough cache space exists to maintain performance. Couchbase Server automatically places items that come into the caching layer into disk queue so that it can write these items to disk. If the server determines that a cached item is infrequently used, it can remove it from RAM to free space for other items. Similarly the server can retrieve infrequently-used items from disk and store them into the caching layer when the items are requested. So the entire process of managing data between the caching layer and data persistence layer is handled entirely by server.