IBM DTCA-24090 Hard Drive Specifications - Page 32

Load/Unload - hdd

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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 uncontrolled, it is more mechanically stressful than a normal unload. A single emergency unload operation is more stressful than 100 normal unloads. Use of emergency unload reduces the start/stop life of the H D D at a rate at least 100x faster than that of normal unload, and may damage the HDD. Warranty is void on a drive that has experienced 3000 or more emergency unloads. 5.3.6.2 Required Power-Off Sequence The required BIOS sequence for removing power from DTCA-2xxxx is: Step 1: Issue one of the following commands. Soft Reset Standby Standby Immediate Sleep | Note: Do not use Flush Cache command 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. Refer to 13.0, "Timings" on page 171 for time out values. Step 3: Terminate power to HDD. 24 OEM Specifications of DTCA-2xxxx 2.5 inch H D D

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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 HDD 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.
A single emergency unload operation is more stressful than 100 normal unloads.
Use of emergency unload
reduces the start/stop life of the HDD at a rate at least 100x faster than that of normal unload, and may
damage the HDD.
Warranty is void on a drive that has experienced 3000 or more emergency unloads.
5.3.6.2
Required Power-Off Sequence
The required BIOS sequence for removing power from DTCA-2xxxx is:
Step 1:
Issue one of the following commands.
Soft Reset
Standby
Standby Immediate
Sleep
|
Note:
Do
not
use Flush Cache command 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.
Refer to 13.0, “Timings” on page 171 for time out values.
Step 3:
Terminate power to HDD.
24
OEM Specifications of DTCA-2xxxx 2.5 inch HDD