Glossary
MTBF
Mean time between failures. The MTBF is calculated by dividing the total operation time (total
MTTR
Mean time to repair. The MTTR is the average time required for a service person to diagnose and repair a faulty drive.
PIO (Programmed input-output)
Mode to transfer data under control of the host CPU
Positioning
Sum of the seek time and mean rotational delay
Power save mode
The power save modes are idle mode, standby mode, and sleep mode.
In idle mode, the drive is neither reading, writing, nor seeking data. In standby mode, the spindle motor is stopped and circuits other than the interface control circuit are sleeping. The drive enters sleep mode when the host issues the SLEEP command.
Reserved
Reserved bits, bytes, and fields are set to zero and unusable because they are reserved for future standards.
Rotational delay
Time delay due to disk rotation. The mean delay is the time required for half a disk rotation. The mean delay is the average time required for a head to reach a sector after the head is positioned on a track.
Seek time
The seek time is the time required for a head to move from the current track to another track. The seek time does not include the mean rotational delay.
Slave (Device 1)
The slave is a second drive that can operate on the AT bus. The slave is daisy- chained with the first drive operating in conformity with the ATA standard.
