Load/Unload - IBM DYLA-28100 - Travelstar 8.1 GB Hard Drive Specifications

5.3.6 Load/Unload

The product supports a minimum of 300,000 normal load/unloads.
Load/unload is a functional mechanism of the HDD. It is controlled by the drive microcode. Specifically,
unloading of the heads is invoked by the commands:
Soft Reset
Standby
Standby Immediate
Sleep
Load/unload is also invoked as one of the idle modes of the drive.
The specified start/stop life of the product assumes that load/unload is operated normally, not in emergency
mode.
5.3.6.1 Emergency Unload
When H D D power is interrupted while the heads are still loaded, the microcode cannot operate and the
normal 5v power is unavailable to unload the heads. In this case, normal unload is not possible, so the
heads are unloaded by routing the back-EMF of the spinning motor to the voice coil. The actuator velocity
is greater than the normal case, and the unload process is inherently less controllable without a normal seek
current profile.
Emergency unload is intended to be invoked in rare situations. Because this operation is inherently uncon-
trolled, it is more mechanically stressful than a normal unload.
DYLA-2xxxx supports a minimum of 20,000 emergency unloads.
5.3.6.2 Required Power-Off Sequence
The required BIOS sequence for removing power from DYLA-2xxxx is:
Step 1: Issue one of the following commands.
Soft Reset
Standby
Standby Immediate
Sleep
Note: Flush Cache command is insufficient for power off sequence, because the command
does not invoke Unload.
Step 2: Wait until Command Complete Status is returned.
In typical case, it takes 350ms for the command completion, however, BIOS time out value needs to be
30sec considering error recovery time.
values.
Step 3: Terminate power to HDD.
This power-down sequence should be followed for entry into any system power-down state, or system
suspend state, or system hibernation state. In a robustly designed system, emergency unload is limited to
rare scenarios such as battery removal during operation.
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O E M Specifications of DYLA-2xxxx 2.5 inch H D D
Refer to 13.0, "Timeout Values" on page 169 for time out