Modify Raid Group Parameters - Fujitsu ETERNUS DX60 S3 User Manual

Chapter 5 RAID Group Management

5.6 Modify RAID Group Parameters

5.6

Modify RAID Group Parameters

This function tunes the following parameters of each RAID group.
• Parameters Setting
- Rebuild Priority
Specify the level to give priority to rebuild, copyback, and redundant copy instead of host access.
Specifying a larger "Rebuild Priority" value may improve rebuild, copyback, and redundant copy
performance.
• Advanced Settings
- DCMF
DCMF is a coefficient for the command issuance amount of the drive. Specify this parameter to improve
the sequential writing access performance. The bigger the value is, the more commands issue.
- Drive Access Priority
This mode controls the command issuance order during drive access. Changing the command issuance
order improves the throughput for all of the drives.
- Throttle
Throttle is the proportion of the number of commands that are issued to a drive at the same time to the
maximum number of commands that can be issued. By limiting the number of commands that are
issued at the same time to the drive, the load on the specific RAID group (drive) is reduced.
- Ordered Cut
Ordered Cut is the number of commands for optimizing drive access processing (priority control). By
performing the priority control of commands in increments of the specified number, a long queue time
for low-priority commands can be eliminated.
• For normal use, it is not necessary to change the default setting of the RAID group parameters.
• When the "Rebuild Priority" setting is changed, the priority is changed not only for a rebuild, copyback,
and redundant copy that will be performed after the setting is changed, but also for any rebuild,
copyback, and redundant copy operations that are currently being performed.
• When the target RAID group is registered as an REC Disk Buffer, do not select "High" for the "Rebuild
Priority" setting. Even if "High" is selected, rebuilding, copyback, and redundant copy are performed with
"Middle" priority during host access.
• Specify the same RAID group parameters for all of the RAID groups that configure a WSV. If different RAID
group parameters are specified, the host access performance may be reduced.
• When specifying "Throttle " or "Ordered Cut", select "Enable" for "Drive Tuning Parameter Setting" in
advance.
• RAID groups that configure a WSV can be checked in the [Volume Detail] screen ([Used RAID Group] tab).
Refer to "Volume Details (Used RAID Group)" in "ETERNUS Web GUI User's Guide (Operation)" for details.
For details on the parameters for this function, refer to
For the factory default settings for this function, refer to
1005).
545
ETERNUS Web GUI User's Guide (Settings)
Copyright 2015 FUJITSU LIMITED
"A.5.5 Modify RAID Group Parameters" (page
"Appendix B Modify RAID Group Parameters" (page
917).
P2X0-1270-13ENZ0