IBM 704 - Manual (Page 174)

Installing Internal Drives
Installing Internal Drives
If you add different types of drives, your system can read multiple
types of media and store more data. Several types of drives are
available, such as:
Hard disk
CD-ROM drive
Tape
Your server contains hardware that lets you replace a failed hard
disk drive without turning off the server. Therefore, you have the
advantage of continuing to operate your system while a hard disk
drive is removed or installed. These drives are known as hot-swap
drives.
Each hot-swap drive bay has three indicator lights visible at the
front of the server. Check the individual indicator lights to
determine which drive is faulty and needs to be swapped out.
When the indicator light indicates a drive fault, you can replace a
hot-swap drive without turning off the server.
12 Hot
Swap Bays
Open Bays
Diskette Drive
CD-ROM
Drive
156 PC Server 704 User's Handbook