Fujitsu ETERNUS DX60 S3 User Manual page 811

Appendix A Parameter List
A.3 Volume Management
• Sequential Slope (SS)
Description
Input condition/
Display contents
• Sequential Dirty Slope (SDS)
Description
Input condition/
Display contents
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.
(End LBA of the previous I/O + 1) + SS (Sequential Slope) 
Start LBA of the current I/O
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.
0 - 4096
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.
(End LBA of the previous I/O + 1) +
SDS (Sequential Dirty Slope)  Start LBA of the current I/O
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.
0 - 4096
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