Fujitsu MAB3045 Product Manual page 102

(3) Caching parameters
The following parameters are used to optimize IDD Read-Ahead caching operations under the
system environments. Refer to Chapter 2 of SCSI Logical Interface Specifications for further
details.
a. Read caching parameters
• RCD:
• WCE:
• MS:
• DISC:
• Number of blocks for which prefetch is suppressed
• Minimum prefetch
• Maximum prefetch
• Number of blocks with maximum prefetch restrictions
• Number of segments
Notes:
1. When Read-Ahead caching operations are disabled by the caching parameter, these
parameter settings have no meaning except write cache feature.
2. Determine the parameters in consideration of how the system accesses the disk.
When the access form is not determined uniquely because of the processing method,
the parameters can be re-set actively.
3. For sequential access, the effective access rate can be increased by enabling Read-
Ahead caching operations and Write Cache feature.
(4) Control mode parameters
The following parameters are used to control the tagged queuing and error logging.
Parameter
Disabling Read-Ahead caching operations
Write Cache Enable
Specifying the multipliers of "minimum
prefetch" and "maximum prefetch"
parameters
Prefetch operation after track switching
during prefetching
C141-E035-02EN
Default value
0 (enabled)
0 (disabled)
0 (Specifying
absolute value)
0 (inhibit)
X'FFFF'
X'0000'
X'0XXX'
(Equivalent to
122 KB)
X'FFFF'
X'4'
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