Lun Concatenation; Figure 33 Lun Concatenation - Fujitsu ETERNUS DX100 S4 Design Manual

2. Basic Functions
Optimization of Volume Configurations

LUN Concatenation

LUN Concatenation is a function that is used to add new area to a volume and so expand the vol-
ume 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 33 LUN Concatenation

RAID5 (3D+1P) 300GB x 4
RAID5 (3D+1P) 300GB x 4
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 levels of the concatenation source vol-
ume and the concatenation destination volume.
When there are concatenation source volumes in SAS disks or Nearline SAS disks, concatenation
can be performed with volumes in SAS disks or Nearline SAS disks.
For SSDs and SEDs, the drives for the concatenation source and destination volumes must be the
same type (SSD or SED).
From a performance perspective, using RAID groups with the same RAID level and the same drives
(type, size, capacity, and rotational speed (for disks), interface speed (for SSDs), and drive enclosure
transfer speed (for SSDs)) is recommended as the concatenation source.
The same key group setting is recommended for the RAID group to which the concatenation
source volumes belong and the RAID group to which the concatenation destination volumes be-
long if the RAID groups are configured with SEDs.
A concatenated volume can be used as an OPC, EC, or QuickOPC copy source or copy destination.
It can also be used as a SnapOPC/SnapOPC+ copy source.
Fujitsu Storage ETERNUS DX100 S4/DX200 S4, ETERNUS DX100 S3/DX200 S3 Hybrid Storage Systems Design Guide (Basic)
LUN0 LUN0
LUN2 LUN2
Concatenation
LUN0 LUN0
LUN2 LUN2
Copyright 2023 Fujitsu Limited
RAID5 (3D+1P) 300GB x 4
LUN1 LUN1
Unused area
Concatenates an
unused area into
LUN2
RAID5 (3D+1P) 300GB x 4
LUN1
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