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C141-E185 5-19
5.6.4 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 IDD to operate by
using the parameter value set by the user when power is turned on again. When the system has
more than one INIT, different parameter value can be set for each INIT.
When the parameters are not set or saved with the MODE SELECT or MODE SELECT
EXTENDED command, the IDD sets the default values for parameters and operates when power is
turned on or after reset. Although the IDD 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 Chapter 3 of SCSI Logical
Interface Specifications for further details of the MODE SELECT and MODE SELECT
EXTENDED commands and specifying the parameters.
IMPORTANT
1. At factory shipment of the IDD, the saving operation for the MODE
SELECT parameter is not executed. So, if the user does not set
parameters, the IDD operates according to the default value of each
parameter
2. The MODE SELECT parameter is not saved for each SCSI ID of but as
the common parameter for all IDs. In the multi-INIT System, parameter
setting cannot be changed for each INIT.
3. Once parameters are saved, the saved value is effective as long as next
saving operation is executed from the INIT. 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 IDD, to which the saving operation has been executed on a
system, is connected to another system, the user must pay attention to
that the IDD operates according to the saved parameter value if the
saving operation is not executed at installation.