Fujitsu MBB2073RC User Manual download pdf (Page 63)

5.4 Checking Operation after Installation and Preparing the HDDs for Use

5.4.3 Setting parameters

The user can specify the optimal operation mode for the user system environments by setting the

following parameters with the MODE SELECT or MODE SELECT EXTENDED command:

• Error recovery parameter

• Caching parameter

• Control mode parameter

With the MODE SELECT or MODE SELECT EXTENDED command, specify 1 for the "SP" bit on

CDB to save the specified parameter value on the disk. This enables the HDDs to operate by using

the parameter value set by the user when power is turned on again.

When the parameters are not set or saved with the MODE SELECT or MODE SELECT

EXTENDED command, the HDDs set the default values for parameters and operates when power is

turned on or after reset. Although the HDD operations are assured with the default values, the

operations are not always optimal for the system. To obtain the best performance, set the parameters

in consideration of the system requirements specific to the user.

This section outlines the parameter setting procedures. Refer to Subsection 4.1.4 “MODE

SELECT (15)”, 4.1.5 “MODE SELECT EXTENDED (55)” of the SAS INTERFACE MANUAL for

further details of the MODE SELECT and MODE SELECT EXTENDED commands and specifying

the parameters.

1. At factory shipment of the HDDs, the saving operation for the MODE

SELECT parameter is not executed. So, if the user does not set

parameters, the HDDs operate according to the default value of each

parameter.

2. The MODE SELECT parameter is not saved for each Loop ID of but as

the common parameter for all initiator. In the multi-initiator system,

parameter setting cannot be changed for each initiator.

3. Once parameters are saved, the saved value is effective as long as next

saving operation is executed from the initiator. For example, even if the

initialization of the disk is performed by the FORMAT UNIT command,

the saved value of parameters described in this section is not affected.

4. When the HDDs, to which the saving operation has been executed on a

system, are connected to another system, the user must pay attention to

that the HDDs operate according to the saved parameter value if the

saving operation is not executed at installation.

5. The saved value of the MODE SELECT parameter is assumed as the

initial value of each parameter after the power-on, the RESET condition.

The initiator can change the parameter value temporary (actively) at any

timing by issuing the MODE SELECT or MODE SELECT EXTENDED

command with specifying "0" to the SP bit in the CDB.

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Fujitsu MBB2073RC User Manual Page 63