Chapter 2 Hardware Installation
Figure 2-4: Installing the BBU Module
2.7 Hard Drive Installation
2.7.1 Hard Drive Installation Prerequisites
CAUTION!
The hard drives and drive trays should only be installed into the subsystem after the subsystem has been mounted into a rack cabinet. If the hard drives are installed first, the subsystem will be too heavy to handle and the possible impact during installation may damage your drives.
WARNING!
Handle hard drives with extreme care. Hard drives are very delicate. 
Formatted: Bullets and Numbering Dropping a drive against a hard surface (even from a short distance)
and hitting or touching the circuits on the drives with your tools may cause damage to the drives.
WARNING!
All drive trays must be installed into the enclosure even if they do not contain a hard drive. If the trays are not installed into the enclosure, the ventilation airflow will not be normalized and the subsystem will overheat.
2.7.2Hard Drive/Drive Tray Installation
Step 1. Make sure the rotary bezel lock is in the unlocked position, i.e., the groove on its face is in a horizontal orientation. If the groove is in a vertical position, as shown
