Fujitsu ETERNUS DX60 S3 User Manual page 673

Appendix A Parameter List
A.1 System Management
• Flexible Write Through
Description
Input condition/
Display contents
•
Do not change the default setting for normal use.
•
If "Enable" is selected for storage systems other than the ETERNUS DX200F, performance for the host I/O may
improve only if all of the following conditions are satisfied. The target is the Write I/O for "Standard (including
concatenation volumes by means of LUN Concatenation)" and "WSV".
-
Sequential write
-
The I/O size from the host is an integral multiple of the basic size (stripe size) for each RAID level.
Refer to
-
If any of the following RAID levels is used:
•
•
•
•
If "Enable" is selected for the ETERNUS DX200F, performance for the host I/O may improve if any of the following
conditions are satisfied.
-
When the RAID level is "Striping (RAID0)", "High Performance (RAID1+0)", or "Mirroring (RAID1)"
The Write I/O for "Standard (including concatenation volumes by means of LUN Concatenation)" and "WSV"
-
When the RAID level is "High Capacity (RAID5)", "Reliability (RAID5+0)", "High Reliability (RAID6)", or "High
Reliability (RAID6-FR)"
The Write I/O for "Standard (including concatenation volumes by means of LUN Concatenation)" and "WSV"
where the I/O size from the host is an integral multiple of the basic size (stripe size) for each RAID group
•
If the cache mode of the ETERNUS DX is in "Write Through Mode", regardless of whether "Flexible Write Through"
is set, all I/Os will be operated with the Write Through mode.
The cache modes for the ETERNUS DX are "Write Back Mode" and "Write Through Mode".
Refer to "System (Basic Information)" in "ETERNUS Web GUI User's Guide (Operation)" for details.
Select whether to enable or disable the Flexible Write Through.
If "Enable" is selected, the cache action is changed only for specific conditions.
•
Enable
For the Flexible Write Through target I/O, by performing a special Write Through
action, data is written to the drive in high speed. Therefore, duplication of the cache
memory and parity is not performed.
By enabling this function in the ETERNUS DX200F, CPU load reduction can be
expected.
For storage systems other than the ETERNUS DX200F, sequential write performance
may improve if I/O size tuning is available from the host (such as with High
Performance Computing).
•
Disable
Changes the cache action according to the cache mode of the ETERNUS DX.
"Appendix F Basic Size and MWC Input Condition for RAID Groups" (page 1054)
RAID5 (2D+1P) - RAID5 (8D+1P)
RAID6 (3D+2P) - RAID6 (8D+2P)
RAID6-FR
-
(3D+2P)x2+1HS
-
(4D+2P)x2+1HS
-
(6D+2P)x2+1HS
-
(5D+2P)x4+1HS
-
(8D+2P)x3+1HS
-
(4D+2P)x5+1HS
-
(3D+2P)x6+1HS
ETERNUS Web GUI User's Guide (Settings)
Copyright 2015 FUJITSU LIMITED
673
for details.
P2X0-1270-13ENZ0