Seagate Savvio 10K Manual download pdf (Page 26)

Savvio SCSI Product Manual, Rev. D

End users should not mix devices with high voltage differential (HVD) drivers and receivers and devices with

SE, LVD, or multimode drivers and receivers on the same SCSI bus since the common mode voltages in the

HVD environment may not be controlled to safe levels for SE and LVD devices (see ANSI SPI-3).

The disc drive spindle must come to a complete stop prior to completely removing the drive from the cabinet

chassis. Use of the Stop Spindle command or partial withdrawal of the drive, enough to be disconnected from

the power source, prior to removal are methods for insuring that this requirement is met. During drive insertion,

care should be taken to avoid exceeding the limits stated in Section 6.4.4, "Shock and vibration" in this manual.

5.2.7 S.M.A.R.T.

S.M.A.R.T. is an acronym for Self-Monitoring Analysis and Reporting Technology. This technology is intended

to recognize conditions that indicate a drive failure and is designed to provide sufficient warning of a failure to

allow data back-up before an actual failure occurs.

Note. The firmware will monitor specific attributes for degradation over time but cannot predict instanta-

neous drive failures.

Each attribute has been selected to monitor a specific set of failure conditions in the operating performance of

the drive, and the thresholds are optimized to minimize “false” and “failed” predictions.

Controlling S.M.A.R.T.

The operating mode of S.M.A.R.T. is controlled by the DEXCPT bit and the PERF bit of the “Informational

Exceptions Control Mode Page” (1Ch). The DEXCPT bit is used to enable or disable the S.M.A.R.T. process.

Setting the DEXCPT bit will disable all S.M.A.R.T. functions. When enabled, S.M.A.R.T. will collect on-line data

as the drive performs normal read/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.

The process of measuring off-line attributes and saving data can be forced by the Rezero Unit command. Forc-

ing S.M.A.R.T. will reset the timer so that the next scheduled interrupt will be two hours.

The drive can be interrogated by the host to determine the time remaining before the next scheduled measure-

ment and data logging process will occur. This is accomplished by a log sense command to log page 0x3E.

The purpose is to allow the customer to control when S.M.A.R.T. interruptions occur. As described above, forc-

ing S.M.A.R.T by the Rezero Unit command will reset the timer.

Performance impact

S.M.A.R.T. attribute data will be saved to the disc for the purpose of recreating the events that caused a predic-

tive failure. The drive will measure and save parameters once every two hours subject to an idle period on the

SCSI bus. The process of measuring off-line attribute data and saving data to the disc is uninterruptable and

the maximum delay is summarized below:

Maximum processing delay

On-line only delay Fully enabled delay

DEXCPT = 0, PERF = 1 DEXCPT = 0, PERF = 0

S.M.A.R.T. delay times 60 milliseconds 370 milliseconds

Reporting control

Reporting is controlled in the Informational Exceptions Control Page (1Ch). Subject to the reporting method,

the firmware will issue a 01-5D00 sense code to the host. The error code is preserved through bus resets and

power cycles.

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Seagate Savvio 10K Manual Page 26