The operation of the La Palma Data Archive is described in detail. The archive contains data taken since early 1986 with the Isaac Newton Group; 74% of the 260,000 entries are of astronomical sources. Several hundreds of queries are made on the catalog each year, resulting in approximately one request per week for data. The rate at which data are retrieved makes the archive (now) roughly the equivalent of 1/3 of a telescope. We discuss the archiving process from the logistics of data taking to maintenance of astronomically relevant information in the catalog and give an indication of the potential of the archive as data resource. A brief discussion of the benefits of an archive is presented in the closing sections.