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2. Basic Functions
Data Protection
The T10-DIF function can be enabled or disabled for each volume when the volumes are created. This function
cannot be enabled or disabled after a volume has been created.
Caution
• The T10-DIF function can be enabled only in the Standard volume.
• LUN Concatenation cannot be performed for volumes where the T10-DIF function is enabled.
Disk Drive Patrol
In the ETERNUS AF, all of the drives are checked in order to detect drive errors early and to restore drives from
errors or disconnect them.
The Disk Drive Patrol function regularly diagnoses and monitors the operational status of all drives that are
installed in the ETERNUS AF. Drives are checked (read check) regularly as a background process.
For drive checking, read check is performed sequentially for a part of the data in all the drives. If an error is
detected, data is reconstructed using drives in the RAID group and the data is written back to another block of
the drive in which the error occurred.
Figure 8
Disk Drive Patrol
Data is read and
checked.
The data is written back
to another block.
Read checking is performed during the diagnosis.
These checks are performed in blocks (default 2MB) for each drive sequentially and are repeated until all the
blocks for all the drives have been checked. Patrol checks are performed every second, 24 hours a day (default).
Note
The Disk Drive Patrol function is suspended during a drive sanitization. After drive sanitization is
completed for all the target drives in the ETERNUS AF, the Disk Drive Patrol function is resumed.
Error detection
Error
D1
RAID group
Data reconstruction
D1
D1
D2
D3
D1
RAID group
D1 to D3: Data
P
P: Parity
33
Design Guide
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