Hitachi HTS543280L9A300, HTS543212L9SA00 Preventive maintenance, Load/unload, Emergency unload

5K320 SATA OEM Specification

6.3.5Preventive maintenance

None.

6.3.6Load/unload

The product supports a minimum of 600,000 normal load/unloads.

Load/unload is a functional mechanism of the hard disk drive. It is controlled by the drive micro code. Specifically, unloading of the heads is invoked by the following commands:

ŸStandby

ŸStandby immediate

ŸSleep

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.

6.3.6.1Emergency unload

When hard disk drive power is interrupted while the heads are still loaded the micro code cannot operate and the normal 5 -volt power is unavailable to unload the heads. In this case, normal unload is not possible. 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.

The drive supports a minimum of 20,000 emergency unloads.

6.3.6.2Required Power-Off Sequence

The required host system sequence for removing power from the drive is as follows:

ŸStep 1: Issue one of the following commands.

ŸStandby

ŸStandby immediate

ŸSleep

Note: Do not use the Flush Cache command for the power off sequence because this command does not invoke Unload.

ŸStep 2: Wait until the Command Complete status is returned.

In a typical case 500 ms are required for the command to finish completion; however, the host system time out value needs to be 30 seconds considering error recovery time.

ŸStep 3: Terminate power to HDD.

This power -down sequence should be followed for entry into any system power -down state, 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.

6.3.6.3Power switch design considerations

In systems that use the Travelstar 5K320 consideration should be given to the design of the system power switch.

Hitachi recommends that the switch operate under control of thehost system, as opposed to being hardwired. The same recommendation is made for cover-close switches. When a hardwired switch is

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