C141-E078-02EN5 - 14
a. Read caching parameters
Parameter Default value
• RCD: Disabling Read-Ahead caching operations 0 (enabled)
• WCE: Write Cache Enable 0 (disabled)
• MS: Specifying the multipliers of "minimum prefetch"
and "maximum prefetch" parameters
0 (Specifying
absolute value)
• DISC: Prefetch operation after track switching during
prefetching
0 (inhibit)
• Number of blocks for which prefetch is suppressed X'FFFF'
• Minimum prefetch X'0000'
• Maximum prefetch X'0XXX'
(1 cache segment)
• Number of blocks with maximum prefetch restrictions X'FFFF'
• Number of segments X'4'
IMPORTANT
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.
a. Control mode parameters
Parameter Default value
• RLEC: Specification of operation when cumulative
value parameter reaches maximum value 0
• Queue algorithm modifier
0 (Does not
report error)
0 (Ordering is
executed by read
command only.)
• QErr: Resume or abort remaining suspended
commands after sense pending state
0 (After release
of sense retention
status, executes
queued command.)
