The Increase Size option on the Pools page allows you to expand the storage capacity of a selected pool by adding new partitions. You can increase the size of your storage pools, but you cannot reduce their size.
In UMC, click Storage > Pools.
Search or browse the servers to list the pools associated with them.
Select the pool, click More Options icon, click Modify, and then select Increase Size.
Select the devices and specify the space to be used from each device.
Only the devices that have free space are listed. If no devices are listed, there is no space available to increase the size of the pool. Click Cancel, add more devices to the server or free up space on the existing devices, then return to the POOLS page to increase the size of the pool.
Click CONFIRM to expand the size of the selected pool.