Hitachi HTS548040M9AT00 Specifications page 41

6.3.6.4 Test considerations
Start/stop testing is classically performed to verify head/disk durability. The heads do not land on the disk, there-
fore this type of test should be viewed as a test of the load/unload function.
Start/Stop testing should be done by commands through the interface, not by power cycling the drive. Simple
power cycling of the drive invokes the emergency unload mechanism and subjects the HDD to nontypical mechan-
ical stress.
Power cycling testing may be required to test the boot-up function of the system. In this case Hitachi recommends
that the power-off portion of the cycle contain the sequence specified in Section 6.3.6.2, "Required Power-Off
Sequence" on page 26. If this is not done, the emergency unload function is invoked and nontypical stress results.
Travelstar 5K80 Hard Disk Drive Specification
27