Hitachi 2.5 inch SATA Travelstar HTS543232L9A300 Oem Specification page 31

5K320 SATA OEM Specification
turned off, emergency unload occurs, as well as the problems cited in section 5.1, "Data loss by power
off" and section 5.2, "Write Cache".
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,
so 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 mechanical 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". If this is not done, the emergency unload function is invoked and
nontypical stress results.
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