Pdm - NEC EXPRESS5800 User Manual

3.11 PDM

The PDM (Predictive Data Migration) feature always monitors HDDs configuring logical drives,
previously senses HDDs suspected to be defected and copies data in the HDDs to spare drives.
Different from the rebuild feature, PDM can be done without degrading of logical drives. After
the data copy, the status display of the source HDDs becomes Stale and they are recognized as
PFA error.
IMPORTANT:
PDM is automatically run under any of the following conditions.
- An S.M.A.R.T. error occurs.
- The number of bad blocks exceeds the threshold (32).
- A fatal error occurs during media patrol.
PDM may also be run manually.
To start PDM manually, follow the procedure below:
1. Select a disk array for which you want to run PDM in the Tree View.
2. Click the arrow at the right end of the Background Activities tab and select Start PDM.
Before the PDM feature can be used, the following
must previously be set.
- Enable PDM is checked in the Settings tab of disk
array. (See the description of the Settings tab in "3.5.7
Disk Array.")
- Spare drives have already been created (if the
automatic PDM feature is used).
If an error occurred in any HDD in logical drive while
the PDM feature is being enabled, the data is copied
onto the spare drive automatically. Consequently, the
slot location initially assigned for a physical drive
configuring logical drives may be changed.
Consideration must be taken into account to use the
PDM feature.
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