Originally, disk drives required a drive bay that was 3.5-inches in height. As technol-
ogy was able to reduce the size of the overall drive, that height was cut in half and now
most of the drive bays available for 5.25-inch devices are less than 2 inches in height and
are calledhalf-height.
Internal versus External Bays
As indicated in the previous paragraph, there are two types of drive bays:
External drive bays These drive bays are actually internal to the case and
chassis, but they can be accessed externally. External drive bays are typically
used for drives that have removable media, such as floppy disks, CD-ROMs,
DVDs, tape drives, and the like.
Internal drive bays These drive bays are completely inside the system case
and are not accessible from outside the chassis, as shown in Figure 15-9. These
bays are designed for devices with no need for external exposure, primarily
hard disk drives.Internal devices can be installed in external bays. Before internal bays were common,
hard disk drives were installed in the external bays, the only kind available, and a solid
face plate was put over the external opening of the bay to hide the drive.
Chapter 15: The System Case^351
Figure 15-9. Internal drive bays inside a chassis. Photo courtesy of Enlight CorporationInternal
drive bays