Any system for re-using baCkup media, e.g. magnetiC tape. One extreme would be to use the same media for every baCkup (e.g. Copy disk A to disk B), the other extreme would be to use new media every time. The trade-off is between the Cost of buying and storing media and the ability to restore any version of any file. One example is the Grandfather, Father, Son (GFS) sCheme. (2004-10-08)