Fujitsu MHT2040BH, Product Manual

Page: 62 / 264

Theory of Device Operation
4-8 C141-E203-01EN
4.5.2 Execution timing of self-calibration
Self-calibration is performed once when power is turned on. After that, the disk
drive does not perform self-calibration until it detects an error.
That is, self-calibration is performed each time one of the following events occur:
•
When it passes from the power on for about 7 or 8 seconds except that the
disk drive shifts to Low Power Idle mode, Standby mode and Sleep mode by
execution of any commands.
•
The number of retries to write or seek data reaches the specified value.
•
The error rate of data reading, writing, or seeking becomes lower than the
specified value.
4.5.3 Command processing during self-calibration
This enables the host to execute the command without waiting for a long time,
even when the disk drive is performing self-calibration. The command execution
wait time is about maximum 72 ms.
When the error rate of data reading, writing, or seeking becomes lower than the
specified value, self-calibration is performed to maintain disk drive stability.
If the disk drive receives a command execution request from the host while
performing self-calibration, it stops the self-calibration and starts to execute the
command. In other words, if a disk read or write service is necessary, the disk
drive positions the head to the track requested by the host, reads or writes data,
and then restarts calibration after about 3 seconds.
If the error rate recovers to a value exceeding the specified value, self-calibration
is not performed.