Change Ownership/Preferred Path - IBM System Storage DS3500 Introduction And Implementation Manual

Draft Document for Review March 28, 2011 12:24 pm
the pre-read check is done online on each read operation and Media Scan checks for
redundancy offline at a predefined time interval in days.
Note: Enabling this feature can influence the overall performance of read operations of the
selected logical drives. This feature should be used for data verification mainly in
environments where data consistency is a key requirement.
To locate this setting, do the following steps:
1. Highlight the logical drive in the Logical pane tree and right click to select Change 
Media Scan Settings. The window shown in Figure 9-31 opens.
Figure 9-31 Change Pre-Read Redundancy Check Settings
2. Select the logical drives that are required for a pre-read redundancy check. You can use
the Ctrl or Shift key to select some of the list, or click Select All to select all of them.
Select the Enable pre-redundancy check... check box and click OK to activate this
feature.
3. Confirm your selection by clicking Yes in next window, wait for the process to complete,
and click OK. When done, you will see a list of LUNs with changed settings.

9.5.5 Change Ownership/Preferred Path

If you are using a dual controller version of the DS3500, each logical drive has a preferred
controller of ownership. This controller normally handles all I/O requests for this particular
logical drive. In other words, each logical drive is owned by one and only one controller. The
alternate controller only takes over and handles the I/O requests in case of a failure along the
I/O path, for example, a defective host bus adapter or switch. When defining logical drives, the
system normally alternates ownership between the two controllers as they are defined.
Situations can occur when all heavily stressed logical drives can reside on only one controller
and the other one handles only a small amount of all I/O requests. To balance the workload
between the controllers, the preferred ownership of a logical drive can be changed to the
other controller.
7914Admin_Logical.fm
Chapter 9. Administration - Logical Tab
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