Lun Concatenation; Figure 34 Lun Concatenation - Fujitsu ETERNUS AF250 Design Manual

1. Function
Optimization of Volume Configurations
For details on the functions that can be executed simultaneously and the number of the process that can be
processed simultaneously, refer to
(page 167).
If drives of different capacities exist in a RAID group that is to be expanded while adding drives, the small-
•
est capacity becomes the standard for the RAID group after expansion, and all other drives are regarded as
having the same capacity as the smallest drive. In this case, the remaining drive space is not used.
Since the data cannot be recovered after the failure of LDE, back up all the data of the volumes in the target
•
RAID group to another area before performing LDE.

LUN Concatenation

LUN Concatenation is a function that is used to add new area to a volume and so expand the volume capacity
available to the server. This function enables the reuse of leftover free area in a RAID group and can be used to
solve capacity shortages.
Unused areas, which may be either part or all of a RAID group, are used to create new volumes that are then
added together (concatenated) to form a single large volume.
The capacity can be expanded during an operation.

Figure 34 LUN Concatenation

RAID5 (3D+1P) RAID5 (3D+1P)
RAID5 (3D+1P) RAID5 (3D+1P)
LUN Concatenation is a function to expand a volume capacity by concatenating volumes.
Up to 16 volumes with a minimum capacity of 1GB can be concatenated.
Concatenation can be performed regardless of the RAID types of the concatenation source volume and the con-
catenation destination volume.
For SSDs and SED SSDs, the drives for the concatenation source and destination volumes must be the same type
(SSD or SED SSD).
From a performance perspective, using RAID groups with the same RAID level and the same drives (type and
capacity) is recommended as the concatenation source.
The same key group setting is recommended for the RAID group to which the concatenation source volumes be-
long and the RAID group to which the concatenation destination volumes belong if the RAID groups are config-
ured with SED SSDs.
"Combinations of Functions That Are Available for Simultaneous Executions"
960GB × 4
LUN0 LUN0
LUN2 LUN2
Concatenation
960GB × 4
LUN0 LUN0
LUN2 LUN2
FUJITSU Storage ETERNUS AF250 S2, ETERNUS AF250 All-Flash Arrays Design Guide (Basic)
Copyright 2019 FUJITSU LIMITED
RAID5 (3D+1P) RAID5 (3D+1P) 960GB × 4
LUN1 LUN1
Unused area
Concatenates an
unused area into
LUN2
RAID5 (3D+1P) RAID5 (3D+1P) 960GB × 4
LUN1
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P3AG-1822-09ENZ0