Disk Drive Patrol; Figure 12 Disk Drive Patrol - Fujitsu ETERNUS DX60 S4 Design Manual

1. Function
Data Protection

Disk Drive Patrol

In the ETERNUS DX, 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 in-
stalled in the ETERNUS DX. 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 restored using drives in the RAID group and the data is written back to another block of the
drive in which the error occurred.

Figure 12 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).
Drives that are stopped by Eco-mode are checked when the drives start running again.
The Maintenance Operation privilege is required to set detailed parameters.
FUJITSU Storage ETERNUS DX60 S4, ETERNUS DX60 S3 Hybrid Storage Systems Design Guide (Basic)
Error detection
Error
D1
RAID group
Data reconstruction
D1
D1
D2 D3
D1
RAID group
D1 to D3: Data
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