Fujitsu ETERNUS DX60 S3 User Manual page 810

Appendix A Parameter List
A.3 Volume Management
• Prefetch Sequential Detect Count (PSDC)
Description
Input condition/
Display contents
• Sequential Dirty Detect Count (SDDC)
Description
Input condition/
Display contents
Specify the Prefetch Sequential Detect Count.
The default PSDC value is "5". It is not necessary to change the default value for normal
use.
If multiple volumes with different settings are selected and [Modify Cache Parameters] is
clicked, the field is blank.
If the host splits data into multiple pieces and performs read access in succession, the
access may be determined as sequential access even if it is actually random access.
When specifying larger PSDC, the required number to detect sequential data for
determining sequential data access is increased and a reduction in performance due to
incorrect prefetch can be avoided. Depending on the amount of sequential data, a large
PSDC slows the determination of sequential data access and performance may be
reduced.
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Specify the value of the Sequential Dirty Detect Count.
The default SDDC value is "5". It is not necessary to change the default value for normal
use.
If multiple volumes with different settings are selected and [Modify Cache Parameters] is
clicked, the field is blank.
If the host splits data into multiple pieces and performs write access in succession, the
access may be determined as sequential access even if it is actually random access.
When specifying larger SDDC, the required number to detect sequential data for
determining sequential data access is increased and a reduction in performance due to
incorrect prefetch can be avoided. Depending on the amount of sequential data, a large
SDDC slows the determination of sequential data access and performance may be
reduced.
1 - 255
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