Load/Unload Specifications; Normal Load/Unload; Emergency Unload; Required Power Off Sequence - Hitachi DK23CA-10 - 10 GB Hard Drive Specifications

3.4 Load/Unload Specifications

Load /Unload is a mechanism to load/unload the heads on the disk surfaces.
3.4.1

Normal Load/Unload

Normal load/unload operations are limited to maximum 300,000 times during HDD life. The normal unload
operation is performed by the following commands.
Standby
-
Standby Immediate
-
Sleep
-
Also, the normal unload is automatically performed by control software, during Idle mode. The above normal
unload time does not include an emergency unload as explained in Sec. 3.4.2.
3.4.2

Emergency Unload

The emergency unload is occurred by unexpected power down, and is limited to maximum 20,000 times
during HDD life. Since normal unload can not be performed by the software control after power off, the
heads are unloaded by a hardware control. The maximum number of emergency unload is defined
separately.
3.4.3

Required Power Off Sequence

To operate the load/unload normally, the following BIOS sequence is required by Host system before power
off.
[Sequence #1]: Execute one of following commands.
- Standby
- Standby Immediate
- Sleep
Note: Such as Soft Reset, Flush Cache command or Check Power Mode command does
[Sequence #2]: Check the Status Register, and wait the command complete.
Note: The head is unload by the sequence #1 command, and the command completion
[Sequence #3]: Power off the drive
Above sequence is required for the Host system at Power off, Suspend and Hibernation operations.
K6602637
Rev.3
02.27.01
not unload the heads. Soft Reset does not unload the heads from DK23CA-xx.
normally takes about 400 ms. Considering the error retries, BIOS timer should be set
to over 30 sec by the Host side.
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