Ceph is structured into libraries which are built and then combined together to make executables and other libraries.
libcommon: a collection of utilities which are available to nearly every ceph library and executable. In general, libcommon should not contain global variables, because it is intended to be linked into libraries such as libcephfs.so.
libglobal: a collection of utilities focused on the needs of Ceph daemon programs. In here you will find pidfile management functions, signal handlers, and so forth.
document other libraries