LVM

from command line

pvdisplay 

lvremove

lvdisplay

see the PV's

pvs
 PV         VG         Fmt  Attr PSize   PFree  
 /dev/sda  vg_1 lvm2 a--  930.82g      0 
 /dev/sdb  vg_1 lvm2 a--  931.31g 931.31g

 lvs -a -o +devices

add a disk to a PV

 vgextend vg_1 /dev/sdb
 Volume group "vg_1" successfully extended

remove a disk from PV

vgreduce vg_1 /dev/sdb
 Removed "/dev/sdb" from volume group "vg_1"

delete a PV

vgremove vg_1
Volume group "vg_1" successfully removed

create a mirror volume

lvcreate -L 931g vg_1 -m 1 vg_1

create a mirror from existing and mounted volume

lvconvert -m1 vg_1/lv_home

• then we check the result:

# pvs;echo;vgs;echo;lvs
 PV         VG         Fmt  Attr PSize   PFree 
 /dev/sda2  vg_1 lvm2 a--  930.82g     0 
 /dev/sdb   vg_1 lvm2 a--  931.31g 56.33g

 VG         #PV #LV #SN Attr   VSize VFree 
 vg_1  2   3   0 wz--n- 1.82t 56.33g

 LV      VG         Attr     LSize   Pool Origin Data%  Move Log          Copy%  Convert
 lv_home vg_1 mwi-aom- 874.98g                         lv_home_mlog 100.00        
 lv_root vg_1 -wi-ao--  50.00g                                                    
 lv_swap vg_1 -wi-ao--   5.84g