Logical Volume Management (LVM) creates a layer of abstraction over physical storage, allowing you to create logical storage volumes. With LVM in place, you are not bothered with physical disk sizes because the hardware storage is hidden from the software so it can be resized and moved without stopping applications or unmounting file systems.
Physical Volume (PV): it is a whole disk or a partition of a disk
Volume Group (VG): corresponds to one or more PV
Logical Volume (LV): represents a portion of a VG. A LV can only belong to one VG. It’s on a LV that we can create a file system.
pvs(pvdisplay) pvscan
===
PV VG Fmt Attr PSize PFree
/dev/sda2 osvg lvm2 a-- <59.00g 0
/dev/sdb oracle_application lvm2 a-- <330.00g <25.00g
vgs (vgdisplay) vgscan
===
VG #PV #LV #SN Attr VSize VFree
oracle_application 1 4 0 wz--n- <330.00g <25.00g
osvg 1 5 0 wz--n- <59.00g 0
lvs (lvdisplay) lvscan
====
LV VG Attr LSize Pool Origin Data% Meta% Move Log Cpy%Sync Convert
app oracle_application -wi-ao---- 5.00g
gridinfra oracle_application -wi-ao---- 100.00g
oracle oracle_application -wi-ao---- 100.00g
orasoftware oracle_application -wi-ao---- 100.00g
homelv osvg -wi-ao---- 4.00g
rootlv osvg -wi-ao---- 19.00g
swaplv osvg -wi-ao---- <16.00g
tmplv osvg -wi-ao---- 12.00g
varlv osvg -wi-ao---- 8.00g
pvcreate /dev/sdb (pvcreate /dev/sdb /dev/sdc)
vgcreate oracle_application /dev/sdb (vgcreate oracle_application /dev/sdb /dev/sdc)
lvcreate -L 5G -n app oracle_application
