System information

Using the RAID GUI
2-21
• Delete logical disks
Select the logical disk(s) you want to delete and click Delete. To delete all LUNs of dgxldy, check the ‘Force to delete
LUN mapping(s)’ box. All access to the logical disk will be stopped.
• Modify logical disks
To modify a setting, select an LD and click Modify. Specify the following options for configuration.
To clear write buffers in the write cache of a logical disk, select a logical disk and click the Flush button.
• Create logical disk (LD) snapshot volume pair
Instead of creating volume pairs in the Snapshot Volumes page, you can directly create volume pair to a specified
logical disk by clicking the S.VOL button. Specify a virtual disk as the secondary volume from the SV ID drop-down menu,
then click the Apply button to confirm.
Alignment Offset
(sector)
Set the alignment offset for the logical disk starting sector to enhance the controller’s
performance. For Windows OS, it is suggested to set the alignment offset at sector
63.
Note
Make sure the disk group to be created for a new logical disk is in OPTIMAL or LD_INIT state,
otherwise the new logical disk will not be created.
Name Type a name for the DG ID/ LD ID.
Preferred Controller This option is only available when the redundant-controller system is in use. Select
the preferred controller to be in charge of managing and accessing the logical disk.
However, the controller ownership will not change unless you check the ‘Change
owner controller immediately’ box.
Write Cache This option enables or disables the write cache of a logical disk.
Write Sorting This option enables or disables the sorting in the write cache. To improve writing
performance, it is recommended to turn this option on for random access. This
option is available only if the write cache is on.
Read Ahead Policy Always: The controller performs pre-fetching data for every read command from
hosts.
Adaptive: The controller performs pre-fetching only for host read commands that
are detected as sequential reads. The detection is done by read logs.
Off: If there is no sequential read command, read-ahead will result in overhead,
and you can disable the read-ahead.
Read Ahead Multiplier This option specifies the read ahead multiplier for the Always and Adaptive read
ahead policies. Select how much additional sequential data will be pre-fetched. The
default value is 8.
Read Logs This option specifies the number of concurrent sequential-read streams for the
Adaptive read ahead policy, and the range is between 1 and 128. The default
value is 32.
LD Read Algorithm This option is only available for logical disks with parity-based RAID level, i.e. RAID
3/5/6.
None: None of the algorithms will be used when accessing data disks.
Intelligent Data Computation: The controller will access logical disks within the
shortest response time. This greatly enhances read performance.
Fast Read Response: When this option is selected, you are prompted to enter the
maximum response time for all read requests. The allowed range for response time
is 100 to 15000 msecs.
Check on Read: This option is similar to the Fast Read Response. In addition to
reading the requested data from disks, the controller will also perform parity check
across corresponding strips on each data disk.