Fujitsu Eternus DX200F, User Manual

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Appendix A Parameter List
A.3 Volume Management
ETERNUS Web GUI User’s Guide (Settings)
Copyright 2015 FUJITSU LIMITED P2X0-1270-13ENZ0
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A.3.8 Modify Cache Parameters
For details about this function, refer to "3.14 Modify Cache Parameters" (page 316) .
For the factory default settings for this function, refer to "Appendix B Modify Cache Parameters" (page 990) .
●
Parameters Setting
• Cache Page Capacity
Description Specify the cache capacity that is used by volumes.
When "-" (hyphen) is selected, the cache capacity is not limited. It is not necessary to
change the default setting for normal use.
If multiple volumes with different settings are selected and [Modify Cache Parameters] is
clicked, a "-" (hyphen) is displayed for the field.
If volumes with a high I/O load exist, data in a low I/O load volume may not stored in the
cache memory and the cache hit rate for the low I/O load volume is reduced. By limiting
the cache capacity that is used by high I/O load volumes, a reduction in performance
when low I/O load volumes are accessed can be prevented.
The cache hit rate for high I/O load volumes is lowered and the access performance for
the volumes may reduced.
Input condition/
Display contents
•
"-" (hyphen)
•
32.50 MB
•
65.00 MB
•
130.00 MB
•
260.00 MB
•
520.00 MB
•
1040.00 MB (Not available for the ETERNUS DX60 S3)
•
2080.00 MB (Not available for the ETERNUS DX60 S3/DX100 S3)
•
Note that this parameter is not used to specify the capacity of dedicated cache for the relevant volume. This
parameter limits the cache capacity that can be used for the relevant volume. Although a volume with this
parameter cannot use a cache memory that exceeds the specified value, other volumes can use the entire
cache, which includes the specified capacity.
•
The cache page capacity must be changed when the I/O load of the volume is low.
•
If write data in the cache memory exceeds the specified cache page capacity for a volume, the cache page
capacity cannot be changed.
•
The cache page capacity cannot be changed for concatenated volumes that are created by the LUN
concatenation function.
•
If the cache page capacity is set, EXC and EXCP of the specified volume is not used (the enabling/disabling of
the EXC and EXCP settings is not changed).
•
When selecting volumes that cannot use this parameter as the target of this function, the "Cache Page Capacity"
and "Current Cache Page Capacity" settings are not displayed on the screen.
•
The specified cache page capacity includes the mirror area. Note that the maximum available cache memory
size used by read I/O is a half the specified value.
•
When the cache page capacity is limited, the capacity cannot be expanded for the relevant volume. Reset the
cache page capacity to the default value before expanding the volume capacity.