IBM DBCA-204860 Hard Drive Specifications - Page 31

Power Switch Design Considerations, 3.6.4, Test Considerations

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5.3.6.3 Power Switch Design Considerations In systems that use DBCA-2xxxxx 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 DBCA-2xxxxx 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 DBCA-2xxxxx invokes the emergency unload mechanism, and subjects the H D D to nontypical mechanical stress. Power cycling testing may be required to test the boot-up function of the system. In this case IBM recommends that the power-off portion of the cycle contain the sequence specified in 5.3.6.2, " Required Power-Off Sequence" on page 22. Again, if this is not done, the emergency unload function is invoked and non-typical stress results. Specification 23

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5.3.6.3
Power Switch Design Considerations
In systems that use DBCA-2xxxxx 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 DBCA-2xxxxx 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 DBCA-2xxxxx invokes the emergency unload mechanism, and subjects the HDD 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 22.
Again, if this is not done, the emergency unload function is invoked and
non-typical stress results.
Specification
23