Logical Device Expansion
Logical Device Expansion (LDE) allows the capacity of an existing RAID group to be dynamically expanded by
changing of the RAID level or the drive configuration of the RAID group. When this function is performed, drives
can be also added at the same time. By using this LDE function to expand the capacity of an existing RAID
group, a new volume can be added without having to add new RAID groups.
•
Expand the RAID group capacity (from RAID5(3D+1P) g RAID5(5D+1P))
Figure 32 Logical Device Expansion (When Expanding the RAID Group Capacity)
RAID5 (3D+1P) 960GB × 4
LUN0
Unused 960GB × 2
RAID5 (5D+1P) 960GB × 6
Expansion
LUN0
Expands the capacity
by adding two drives
•
Change the RAID levels (from RAID5(3D+1P) g RAID1+0(4D+4M))
Figure 33 Logical Device Expansion (When Changing the RAID Level)
RAID5 (3D+1P) 960GB × 4
LUN0
Unused 960GB × 4
RAID1+0 (4D+4M) 960GB × 8
Expansion
LUN0
LUN0
Expands the capacity b
y
adding four drives and
changes the RAID level
LDE works in terms of RAID group units. If a target RAID group contains multiple volumes, all of the data in the
volumes is automatically redistributed when LDE is performed. Note that LDE cannot be performed if it causes
the number of data drives to be reduced in the RAID group.
In addition, LDE cannot be performed for RAID groups in which the following conditions apply.
•
RAID groups that belong to TPPs or FTRPs
•
The RAID group that is registered as an REC Disk Buffer
•
RAID groups in which WSVs are registered
•
RAID groups that are configured with RAID5+0 or RAID6-FR
LDE may not be available when other functions are being used in the
ETERNUS AF or the target RAID group.
1. Function
Optimization of Volume Configurations
61
FUJITSU Storage ETERNUS AF250 S2, ETERNUS AF250 All-Flash Arrays
Design Guide (Basic)
Copyright 2019 FUJITSU LIMITED
P3AG-1822-09ENZ0
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