IBM DYLA-28100 - Travelstar 8.1 GB Hard Drive Specifications page 33

5.3.6.3 Power Switch Design Considerations
In systems that use DYLA-2xxxx consideration should be given to the design of the system power switch.
IBM recommends that the switch operate under control of the Bios, as opposed to being 'hard wired'. The
same recommendation is made for 'cover-close' switches. When a hard wired switch is turned off, emergency
unload occurs, as well as the problems cited in 4.1, " Data Loss by Power Off" on page 15 and 4.2, " Write
Cache" on page 15.
5.3.6.4 Test Considerations
Start/stop testing is classically performed to verify head/disk durability. In the case of DYLA-2xxxx 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 DYLA-2xxxx invokes the emergency unload mechanism, and subjects the H D D to non-
typical mechanical stress.
Power cycling testing may be required to test the boot-up function of the system. In this case IBM recom-
mends that the power-off portion of the cycle contain the sequence specified in 5.3.6.2, " Required
Power-Off Sequence" on page 24. Again, if this is not done, the emergency unload function is invoked and
non-typical stress results.
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Specification