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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
1. When Read-Ahead caching operations are disabled by the
2. Determine the parameters in consideration of how the system
3. For sequential access, the effective access rate can be increased
(4)
Control mode parameters
The following parameters are used to control the tagged queuing and error logging.
a. Control mode parameters
• RLEC:
• Queue algorithm modifier
• QErr:
5 - 14
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
IMPORTANT
caching parameter, these parameter settings have no meaning
except write cache feature.
accesses the disk. When the access form is not determined
uniquely because of the processing method, the parameters can
be re-set actively.
by enabling Read-Ahead caching operations and Write Cache
feature.
Parameter
Specification of operation when cumulative
value parameter reaches maximum value 0
Resume or abort remaining suspended
commands after sense pending state
C141-E078-02EN
Default value
0 (enabled)
0 (disabled)
0 (Specifying
absolute value)
0 (inhibit)
X'FFFF'
X'0000'
X'0XXX'
(1 cache segment)
X'FFFF'
X'4'
Default value
0 (Does not
report error)
0 (Ordering is
executed by read
command only.)
0 (After release
of sense retention
status, executes
queued command.)
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