Lun Concatenation; Figure 28 Lun Concatenation; Figure 29 Lun Concatenation (When The Concatenation Source Is A New Volume) - Fujitsu ETERNUS DX60 S4 Design Manual

1. Function
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 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 28 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.
When there are concatenation source volumes in SAS disks or Nearline SAS disks, concatenation can be per-
formed with volumes in SAS disks or Nearline SAS disks.
For SSDs, the drives for the concatenation source and destination volumes must be the same type (SSD).
From a performance perspective, using RAID groups with the same RAID level and the same drives (type, size,
capacity, and rotational speed) is recommended as the concatenation source.
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.
The LUN number stays the same before and after the concatenation. Because the server-side LUNs are not
changed, an OS reboot is not required. Data can be accessed from the host in the same way regardless of the
concatenation status (before, during, or after concatenation). However, the recognition methods of the volume
capacity expansion vary depending on the OS types.
When the concatenation source is a new volume
•
A new volume can be created by selecting a RAID group with unused capacity.

Figure 29 LUN Concatenation (When the Concatenation Source Is a New Volume)

+
10GB
FUJITSU Storage ETERNUS DX60 S4, ETERNUS DX60 S3 Hybrid Storage Systems Design Guide (Basic)
LUN0 LUN0
LUN2 LUN2
Concatenation
LUN0 LUN0
LUN2 LUN2
+
20GB 30GB
Unused area
Copyright 2019 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
Concatenation
60GB
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P3AM-8992-14ENZ0