User guide

3.11 PDM
The PDM (Predictive Data Migration) feature constantly monitors the HDDs configuring the
logical drives, identifies HDDs about to fail and copies the data from these HDDs to the spare
drives. Different from the rebuild feature, PDM can be done without degrading the logical
drives. Once the data is copied, the status display of the source HDDs becomes Stale and they
are recognized as in PFA error.
IMPORTANT:
 Set the following before using the PDM feature:
- Check Enable PDM in the Settings tab of the disk array. (See the
description of the Settings tab in "3.5.7 Disk Array.")
- Create the Spare drives (if the automatic PDM feature is used).
 If an error occurred in any HDD of a logical drive while the PDM
feature is enabled, the data is copied onto the spare drive automatically.
Consequently, the slot location initially assigned for the physical drives
configuring the logical drives may change. This consideration must be
taken into account when using the PDM feature.
The PDM automatically runs under any of the following conditions:
- A S.M.A.R.T. error occurs.
- The number of bad blocks exceeds the threshold (32).
- A fatal error occurs during media patrol.
The PDM may also be run manually.
To start the PDM manually, follow the procedure below:
1. Select a disk array for which you want to run the PDM in the Tree View.
2. Click the arrow at the right end of the Background Activities tab and select Start PDM.
3. Specify the following.
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