Appendix A Parameter List
A.3 Volume Management
ETERNUS Web GUI User’s Guide (Settings)
Copyright 2015 FUJITSU LIMITED P2X0-1270-13ENZ0
811
• Sequential Slope (SS)
• Sequential Dirty Slope (SDS)
Description Specify the value of the Sequential Slope.
If the following equation is true for sequential data access (Read I/O), the access is
determined as sequential access. The default SS value is "128". 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.
The following conditions can be also determined as sequential access.
• A sequential access that does not have successive LBAs.
• A sequential access that issues multiple host I/Os at the same time and is unable to
be received in the order of LBAs.
A larger SS may cause random access to be determined as sequential access, resulting in
reduced performance due to incorrect prefetching.
Input condition/
Display contents
0 - 4096
Description Specify the value of the Sequential Dirty Slope.
If the following equation is true for sequential data access (Write I/O), the access is
determined as sequential access. The default SDS value is "128". 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.
The following conditions can be also determined as sequential access.
• A sequential access that does not have successive LBAs.
• A sequential access that issues multiple host I/Os at the same time and is unable to
be received in the order of LBAs.
A larger SDS may cause random access to be determined as sequential access, resulting
in reduced performance due to incorrect prefetching.
Input condition/
Display contents
0 - 4096
(End LBA of the previous I/O + 1) + SS (Sequential Slope)
Start LBA of the current I/O
(End LBA of the previous I/O + 1) +
SDS (Sequential Dirty Slope) Start LBA of the current I/O
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