Only one Volume to select when creating PureDisk disk pool on Media Server - 7.5.0.7

I have two Windows 2008 R2 clustered servers running NetBackup 7.5.0.7 as a master server.

I have 15 LUNs from 3PAR storage as PV on Redhat media server. Then I created VG and LV, file system is ext4, 15T size.

First problem: When I creating a storage server, using Media Server Dudepelication Pool type, I don't know where to put the "storage path" and how much

space does it need ?

Second problem：After I created storage server, there is only one volume to select when creating PureDisk disk pool. This one is my root LV.

The 15T LV can't display on the selections.

Please help ,thx!