You might see or hear references to "master" and "slave" drives in your computer and wonder what they are. In terms of their status, the master drive is the one in command, while the slave drive is the one taking the orders.
Hierarchy
The master (primary) hard drive is the main bootable drive plugged directly into the IDE cable from the computer's motherboard. When you start your computer, the motherboard will primarily address the master hard drive to set the computer in motion. The slave (secondary) drive will operate as an auxiliary storage drive.
Storage
Slave drives are mostly used for storing data to protect it in the event of a system crash. Master drives usually contain the operating system to run the computer. Computers without a secondary drive set as a slave drive will store their data on the main (only) hard drive, alongside the operating system.
Jumper Settings
A slave (secondary) hard drive needs no jumper settings. When a slave drive is installed, the master drive (the primary drive) must have a designated configuration to tell the computer which drive is the primary boot drive.