Rebuild; Figure 14 Rebuild - Fujitsu ETERNUS DX100 S4 Design Manual

2. Basic Functions
Data Protection
Redundant Copy speed
•
Giving priority to Redundant Copy over host access can be specified. By setting a higher Re-
build priority, the performance of Redundant Copy operations may improve.
However, it should be noted that when the priority is high and a Redundant Copy operation is
performed for a RAID group, the performance (throughput) of this RAID group may be re-
duced.

Rebuild

Rebuild processes recover data in failed drives by using other drives. If a free hot spare is available
when one of the RAID group drives has a problem, data of this drive is automatically replicated in
the hot spare. This ensures data redundancy.

Figure 14 Rebuild

Failure
Disconnection
Failed drive
When no hot spares are registered, rebuilding processes are only performed when a failed drive
is replaced or when a hot spare is registered.
Rebuild Speed
•
Giving priority to rebuilding over host access can be specified. By setting a higher rebuild prior-
ity, the performance of rebuild operations may improve.
However, it should be noted that when the priority is high and a rebuild operation is performed
for a RAID group, the performance (throughput) of this RAID group may be reduced.
Fujitsu Storage ETERNUS DX100 S4/DX200 S4, ETERNUS DX100 S3/DX200 S3 Hybrid Storage Systems Design Guide (Basic)
RAID5 (No redundancy)
RAID5 (Redundant)
34
Copyright 2023 Fujitsu Limited
Rebuild
Disconnects the failed drive to the
ETERNUS storage system and
creates data from the drives other
than the failed drive and writes the
data into the hot spare.
Hot spare
Configures the hot spare in the
RAID group.
P3AM-7642-32ENZ0