You can create any size of custom-sized volumes (CVs) by using Virtual LUN.
When multiple frequently accessed files are contained on the same logical volume, if one file is being accessed, an access to a different file might be delayed. Virtual LUN divides the logical volume into smaller multiple logical volumes to distribute the files across the divided logical volumes. This generally reduces the access conflicts and improves the data accessing performance.
To create CVs, first you delete one or more CVs in an external volume group to create free space, and then you can create any size of CVs in the created free space.
The following diagram shows how CVs are created.
To create LDEVs, use the Virtual LUN function. Open Volume Management software is required to use Virtual LUN function.
Volume configuration in an external volume group when using Virtual LUN
LDEV creation and LDEV deletion by using Virtual LUN is performed for each external volume group. The boundary constraints per RAID level also applies to each external volume group,. Therefore, volumes cannot be defined across external volume groups (between external volume groups).
As a result of the Virtual LUN operations, the external volume group contains CVs and free space that are individually separated into logical cylinders. Multiple consecutive free spaces can be combined into one free space.