Seagate ST400FX0012, ST100FX0002, ST200FX0002, ST400FX0002 Predictive failures, Thermal monitor

Error rate is the number of errors per operation. The algorithm that S.M.A.R.T. uses to record rates of error is to set thresholds for the number of errors and appropriate interval. If the number of errors exceeds the threshold before the interval expires, the error rate is considered to be unacceptable. If the number of errors does not exceed the threshold before the interval expires, the error rate is considered to be acceptable. In either case, the interval and failure counters are reset and the process starts over.

Predictive failures

S.M.A.R.T. signals predictive failures when the drive is performing unacceptably for a period of time. The firm- ware keeps a running count of the number of times the error rate for each attribute is unacceptable. To accom- plish this, a counter is incremented each time the error rate is unacceptable and decremented (not to exceed zero) whenever the error rate is acceptable. If the counter continually increments such that it reaches the pre- dictive threshold, a predictive failure is signaled. This counter is referred to as the Failure History Counter. There is a separate Failure History Counter for each attribute.

6.3.5Thermal monitor

Pulsar XT.2 drives implement a temperature warning system which:

1.Signals the host if the temperature exceeds a value which would threaten the drive.

2.Signals the host if the temperature exceeds a user-specified value. (i.e., the reference temperature value)

3.Saves a S.M.A.R.T. data frame on the drive which exceeds the threatening temperature value.

A temperature sensor monitors the drive temperature and issues a warning over the interface when the tem- perature exceeds a set threshold. The temperature is measured at power-up and then at ten-minute intervals after power-up.

The thermal monitor system generates a warning code of 01-0B01 when the temperature exceeds the speci- fied limit in compliance with the SCSI standard. The drive temperature is reported in the FRU code field of MODE SENSE data. Administrators can use this information to determine if the warning is due to the tempera- ture exceeding the drive threatening temperature or the user-specified temperature.

This feature is controlled by the Enable Warning (EWasc) bit, and the reporting mechanism is controlled by the Method of Reporting Informational Exceptions field (MRIE) on the Informational Exceptions Control (IEC) mode page (1Ch).

The current algorithm implements two temperature trip points. The first trip point is set at the maximum temper- ature limit according to the drive specification. The second trip point is user-selectable using the LOG SELECT command. The reference temperature parameter in the temperature log page (see Table 7) can be used to set this trip point. The default value for this drive is listed in the table, however, applications can set it to any value in the range defined. If a temperature is specified that is greater than the maximum allowed in this field, the temperature is rounded down to the maximum allowed. A sense code is sent to the host to indicate the round- ing of the parameter field.

Table 7:	Temperature Log Page (0Dh)
Parameter Code		Description		400GB	200/100GB
0000h		Primary Temperature		Drive Temperature
0001h		Reference Temperature	Default Setting	70°C	65°C
			Changeable Range	0 to 70°C	0 to 65°C

18 Pulsar XT.2 SAS Product Manual, Rev. B