Virtual LUN functions
Virtual LUN function is used to create, configure, or delete a customized volume (LDEV).
The Virtual LUN function is an open systems function available in Open Volume Management software.
A parity group usually consists of some fixed-sized volumes (FVs) and some free space. The number of FVs is determined by the emulation type. A Virtual LUN volume usually consists of at least one FV, one or more customized volumes (CVs), and some free space.
Use the Virtual LUN function to configure variable-sized volumes that efficiently exploit the capacity of a disk. Variable-sized volumes are logical volumes that are divided into smaller than normal fixed-size volumes. This configuration is desirable when frequently accessed files are distributed across smaller multiple logical volumes. This generally improves the data accessing performance, though file access may be delayed in some instances.
The Virtual LUN function can also divide a logical volume into multiple smaller volumes to reduce unused capacity and provide a more efficient use of space for small volumes such as command devices. The Virtual LUN function can efficiently exploit the capacity of a disk by not wasting capacity using larger volumes when the extra capacity is not needed.