JSTOR is a full-text journal archive that includes over 1,400 leading academic journals and primary source materials valuable for academic work. The entire archive is full-text searchable, includes images and multi-media files, and is interlinked by millions of citations and references.
JSTOR includes some sixty-three music journals, more than that if you count supplemental publications. Most of these have moving walls, meaning that the last few years are not available (typically one to five years depending on the individual journal’s policy). Most of the journals are full runs (excluding the moving walls) and some of them go as far back as the nineteenth century.
JSTOR has recently begun adding books to its collection and now has over 450 relatively recent books in music.