5.2.1Mean Time Between Failure (MTBF)
The production disc drive shall achieve an MTBF of 1,000,000 hours when operated in an environment that ensures the HDA case temperatures specified in Section 6.4 are not exceeded. Short-term excursions up to the specification limits of the operating environment will not affect MTBF performance. Continual or sustained operation at case temperatures above the values shown in Section 6.4.1 may degrade product reliability.
Estimated power-on operation hours means power-up hours per disc drive times the total number of disc drives in service. Each disc drive shall have accumulated at least nine months of operation. Data shall be cal- culated on a rolling average base for a minimum period of six months.
MTBF is based on the following assumptions:
•8,760 power-on hours per year.
•250 average on/off cycles per year.
•Operations at nominal voltages.
•Systems will provide adequate cooling to ensure the case temperatures specified in Section 6.4.1 are not exceeded.
Drive failure means any stoppage or substandard performance caused by drive malfunction.
A S.M.A.R.T. predictive failure indicates that the drive is deteriorating to an imminent failure and is considered an MTBF hit.
5.2.2Preventive maintenance
No routine scheduled preventive maintenance is required.
5.2.3Hot plugging the drive
Inserting and removing the drive on the FC-AL will interrupt loop operation. The interruption occurs when the receiver of the next device in the loop must synchronize to a different input signal. FC error detection mecha- nisms, character sync, running disparity, word sync, and CRC are able to detect any error. Recovery is initiated based on the type of error.
The disc drive defaults to the FC-AL Monitoring state, Pass-through state, when it is powered-on by switching the power or hot plugged. The control line to an optional port bypass circuit (external to the drive), defaults to the Enable Bypass state. If the bypass circuit is present, the next device in the loop will continue to receive the output of the previous device to the newly inserted device. If the bypass circuit is not present, loop operation is temporarily disrupted until the next device starts receiving the output from the newly inserted device and regains synchronization to the new input.
The Pass-through state is disabled while the drive performs self test of the FC interface. The control line for an external port bypass circuit remains in the Enable Bypass state while self test is running. If the bypass circuit is present, loop operation may continue. If the bypass circuit is not present, loop operation will be halted while the self test of the FC interface runs.
When the self test completes successfully, the control line to the bypass circuit is disabled and the drive enters the FC-AL Initializing state. The receiver on the next device in the loop must synchronize to output of the newly inserted drive.
If the self-test fails, the control line to the bypass circuit remains in the Enable Bypass state.
Note. It is the responsibility of the systems integrator to assure that no temperature, energy, voltage haz- ard, or ESD potential hazard is presented during the hot connect/disconnect operation. Discharge the static electricity from the drive carrier prior to inserting it into the system.
Caution. The drive motor must come to a complete stop prior to changing the plane of operation. This time is required to insure data integrity.
