Operation Mode Setting; Parameters For Controlling Reconnection Timing - Fujitsu MAA3182FC Series Manual

3.1.2

Operation mode setting

(1) MODE SELECT parameter
In order to make it possible to control from the INIT the Loop OPEN processing start timing
for executing data transfers to the FC interface in read and write operations, the IDD is
provided with the MODE SELECT parameter (Disconnect/Reconnect Parameter: Page code =
2) shown in Figure 3.4.
environment as necessary. The IDD holds the MODE SELECT parameter individually for
each INIT's SCSI ID, so the specified parameter values can differ for each INIT. See Section
4.1.5 for details of the MODE SELECT command.
[Disconnect/Reconnect Parameter (Page code = 2)]
Bit 7
Byte
0 0
1
2
3
4
~ ~
(Other parameters)
~ ~
15
Figure 3.4
a. Buffer full ratio
This parameter specifies the timing for the IDD to open the loop to perform data transfer to
the INIT in a READ or READ EXTENDED command.
The value specified in this parameter (n) shows the amount of data read to the IDD's data buffer
from the disk media as a proportion [n/256] of the total capacity of the data buffer until
reconnection processing with the SCSI bus is started. The IDD's default cache segment capacity
is 972 KB (MAA3182FC) and 486 KB (MAF3364FC, MAG3091FC, MAG3182FC).
Therefore, if the specified value (n) is 128, for example, it means that a data volume of 243 KB
was specified (Note)
If it is possible to transfer the amount of data specified in this parameter to the INIT from
the data buffer, Loop OPEN processing is executed and transfer of data to the INIT begins.
However, if the total amount of transfer data specified in the command does not fill the
capacity of the cache segment, the IDD executes Loop OPEN processing and begins
transferring data to the INIT when it becomes possible to transfer the amount of data
blocks from the data buffer which is equivalent to the proportion of the total volume of
transfer data blocks specified in the command that is specified by this parameter.
The user can set the optimum operating state in the system
6 5 4
0 0 0
X'0E' (Page Length)
Buffer Full Ratio
Default Value: X'20' (=1/8 of cache segment capacity)
Variable Range: X'00' to X'FF'
Buffer Empty Ratio
Default Value: X'20' (=1/8 of cache segment capacity)
Variable Range: X'00' to X'FF'

Parameters for controlling reconnection timing

C141-E054-02EN
3 2 1
0 0 1
0
0
~
~
3 - 5