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5.4 Checking Operation after Installation and Preparing the HDD for Use
C141-E235 5-11
5.4.4 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
• Disconnection/reconnection 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 HDD to operate by using
the parameter value set by the user when power is turned on again. When the system has more than
one initiator, different parameter value can be set for each initiator.
When the parameters are not set or saved with the MODE SELECT or MODE SELECT
EXTENDED command, the HDD sets 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 Fibre Channel Interface
Specifications for further details of the MODE SELECT and MODE SELECT EXTENDED
commands and specifying the parameters.
1. At factory shipment of the HDD, the saving operation for the MODE
SELECT parameter is not executed. So, if the user does not set
parameters, the HDD operates according to the default value of each
parameter
2. The model select parameter is not saved for each Loop ID of but as the
common parameter for all IDs. 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 HDD, to which the saving operation has been executed on a
system, is connected to another system, the user must pay attention to
that the HDD operates 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,
or the BUS DEVICE RESET message. 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.