Fast Recovery
This function recovers data quickly by relocating data in the failed drive to the other remaining
drives when a drive error is detected.
For a RAID group that is configured with RAID6-FR, Fast Recovery is performed for the reserved
area that is equivalent to hot spares in the RAID group when a drive error occurs.
If a second drive fails when the reserved area is already used by the first failed drive, a normal re-
build (hot spare rebuild in the
ETERNUS DX) is performed.
For data in a failed drive, redundant data and reserved space are allocated in different drives ac-
cording to the area. A fast rebuild can be performed because multiple rebuild processes are per-
formed for different areas simultaneously.
Figure 15 Fast Recovery
Failed drive
RAID6-FR ((3D+2P) × 2)
RAID6-FR (No redundancy)
: Redundant data for area A
of the failed drive
: Redundant data for area B
of the failed drive
: Fast recovery Hot Spare (FHS)
Failure
RAID6-FR ((3D+2P) × 2 + 1HS)
High Speed Rebuilding
(Creating data and writing to the FHS area
simultaneously)
Disconnect
RAID6-FR (Redundant)
A f
ailed drive is disconnected from
the ETERNUS storage system.
Data is created from the redundant
data in normal drives and written to
reserved space (FHS) in RAID6-FR.
For the Fast Recovery function that is performed when the first drive fails, a copyback is per-
formed after the failed drive is replaced even if the Copybackless function is enabled.
For a normal rebuild process that is performed when the reserved space is already being used
and the second drive fails, a copyback is performed according to the settings of the Copyback-
less function.
2. Basic Functions
Data Protection
35
Fujitsu Storage ETERNUS DX100 S4/DX200 S4, ETERNUS DX100 S3/DX200 S3 Hybrid Storage Systems
Design Guide (Basic)
Copyright 2023 Fujitsu Limited
P3AM-7642-32ENZ0
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