IBM R30 Operator's Manual page 131

Disk Drive
There are no operator controls on the disk drive.
Because data can become unusable if a disk drive problem occurs, you should back up the
data stored on the disks. See your operating system documentation for information about
using diskettes or tape drives to back up files.
Controls
Under normal conditions, you do not use the controls located behind the cover of the SCSI
drawer. Power to the drawer is switched on and off automatically when power to the CPU
enclosure is switched on and off.
4-9
AC Rack Description