Lun Concatenation - Fujitsu ETERNUS DX80 S2 User Manual

Chapter 3 Setup
3.7 Optimizing Volume Configurations
3.7.3

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. The ability to concatenate widely distributed free areas in the ETERNUS DX Disk
storage system allows efficient use of the drive capacity.
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.
This section describes the restrictions and notes on using LUN Concatenation.
For details on the LUN Concatenation procedure, refer to "ETERNUS Web GUI User's Guide" or "ETERNUS CLI
User's Guide".
• Volumes can be specified as a target for LUN Concatenation.
• Multiple volumes can be concatenated. Up to 16 volumes can be concatenated.
• Maximum concatenated volume capacity is 128TB (*1).
*1: The maximum volume capacity of an ODX Buffer volume is 1TB.
• The minimum required capacity of each volume being concatenated is 1GB.
• Conditions for volumes to be concatenated are as follows:
- Only Standard/Open type volumes can be used for LUN Concatenation. SDV cannot be concatenated.
The encryption status of a concatenated volume is the same status as a volume that is to be
concatenated.
- The RAID levels may be any that are supported by the ETERNUS DX Disk storage system with no need for
all to be the same or any other limitation. It is also possible to connect up volumes with different RAID
levels. Volumes in RAID groups with different types (such as capacity or speed) of drives can be concat-
enated. However, RAID groups with the same RAID level and same drive type are recommended for con-
catenated volumes to ensure that performance is not affected.
- LUN Concatenation cannot be performed when the drive type for the RAID group to which the
concatenation source volume belongs and the drive type to which the concatenation target volume
belongs do not match.
• When the concatenation source volume is configured with SAS disks or Nearline SAS disks, volumes
that are configured with SAS disks or Nearline SAS disks can be concatenated.
• When the concatenation source volume is configured with SSDs, volumes that are configured with
SSDs can be concatenated.
• When the concatenation source volume is configured with SEDs, volumes that are configured with
SEDs can be concatenated.
- 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 belong if the
RAID groups are configured with SEDs.
• LUN Concatenation cannot be performed under the following conditions:
- When the volume to be concatenated contains an Advanced Copy session for which the copy range is
"Totally".
- When the volume to be concatenated is a TPV or an FTV.
- When the number of volumes to be concatenated is fewer than the maximum number of volumes that
can be concatenated but the resulting capacity exceeds the maximum single LUN capacity allowed by
the ETERNUS DX Disk storage system.
- When the logical volume to be concatenated is a WSV.
• The encryption status after concatenation is the same as the concatenation source volume.
• It is possible to add extra volumes to an already concatenated volume.
• After concatenation, any number of formatting processes can be started at once.
ETERNUS DX80 S2/DX90 S2 Disk storage system User's Guide -Operation-
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