How to think Linux volume system Here is the coprehensive image from Wikipedia.
From Wikipedia There are several physical volumes (PVs) in a server. Linux group the physical volumes in a volume group (a VG). Each of PVs contains physical partitions (PPs). We can aggregate the PVs in a logical volume (a LV). On a LV, we can decide a file system (FS). From Linux side, we can mount a Linux directory to the FS.