a system and method for backing up and restoring data from client computers at a server computer . the server computer receives back - up data from individual client computers and inserts them into a configurable buffer within a shared memory area . the server associates a client identification tag with each set of back - up data which identifies from which particular client computer the data was received . buffer availability flags determine whether a buffer associated with a client server is full or available . the server multiplexes the back - up data and the identification tags onto a tape . data from a particular client is de - multiplexed from the tape by scanning all of the identification tags on the tape and pulling off the tape any data - which is associated with the identification tag corresponding to the particular client . an additional back - up scheduler unit using configurable parameters enables the entire multiplexed data back - up process to be tailored to the performance capabilities of an individual set of client / server computer resources such as by limiting how many client computer back - up jobs may be written to a single tape drive .