Seagate ST373554FC ユーザーズマニュアル

Cheetah 15K.4 FC Product Manual, Rev. B

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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.

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.

The drive motor must come to a complete stop prior to changing the plane of operation. This time is 
required to insure data integrity.

S.M.A.R.T. is an acronym for Self-Monitoring Analysis and Reporting Technology. This technology is intended 
to recognize conditions that indicate imminent drive failure and is designed to provide sufficient warning of a 
failure to allow you to back up the data before an actual failure occurs.

The drive’s firmware monitors specific attributes for degradation over time but can’t predict instanta-
neous drive failures.

Each monitored attribute has been selected to monitor a specific set of failure conditions in the operating per-
formance of the drive and the thresholds are optimized to minimize “false” and “failed” predictions.

The operating mode of S.M.A.R.T. is controlled by the DEXCPT and PERF bits on the Informational Exceptions 
Control mode page (1Ch). Use the DEXCPT bit to enable or disable the S.M.A.R.T. feature. Setting the DEX-
CPT bit disables all S.M.A.R.T. functions. When enabled, S.M.A.R.T. collects on-line data as the drive performs 
normal read and write operations. When the PERF bit is set, the drive is considered to be in “On-line Mode 
Only” and will not perform off-line functions.

You can measure off-line attributes and force the drive to save the data by using the Rezero Unit command. 
Forcing S.M.A.R.T. resets the timer so that the next scheduled interrupt is in one hour.

You can interrogate the drive through the host to determine the time remaining before the next scheduled mea-
surement and data logging process occurs. To accomplish this, issue a Log Sense command to log page 0x3E. 
This allows you to control when S.M.A.R.T. interruptions occur. Forcing S.M.A.R.T. with the RTZ command 
resets the timer.