Let’s assume that you want to increase 1Gb of the /dev/MyVG /lvol1 device (mounted as /filesystem):
# bdf /filesystem
Filesystem          kbytes    used   avail %used Mounted on
/dev/ MyVG /lvol1
                   573440000 533892407 37080557   94% /filesystem

The actual size is 573440000 Kb (573 Gb) and you will increase it to 574440000 Kb (574 Gb).

- Check if there is available space in the Volume Group:
# vgdisplay MyVG
--- Volume groups ---
VG Name                     /dev/MyVG
VG Write Access             read/write
VG Status                   available
Max LV                      255
Cur LV                      1
Open LV                     1
Max PV                      100
Cur PV                      17
Act PV                      17
Max PE per PV               15000
VGDA                        34
PE Size (Mbytes)            16
Total PE                    36907
Alloc PE                    35000
Free PE                     1907
Total PVG                   1
Total Spare PVs             0
Total Spare PVs in use      0

Note the “Free PE” and “PE Size (Mbytes)”. It say that you has 30512 Mb (30Gb) available in MyVG (Free PE * PE Size).

- Increase the lvol:
# lvextend -L 574440 /dev/MyVG/lvol1
* the syntax is: lvexten -L <new size in Mb> <lvol path>

- Now, increase the filesystem:
# fsadm -b 574440m /filesystem
* the syntax is: fsadm –b <new size in Mb> <mount point>