extnending a logical volume
                    based on the following information does my lvextend command look ok:
lvdisplay /dev/VolGroup02/u03 shows this
 - lv name = /dev/VolGroup02/u03
 - vg name = VolGroup02
 df /u03 
Filesystem           1K-blocks      Used Available Use% Mounted on
/dev/mapper/VolGroup02-u03
                     103212320  77407636  20561804  80% /u03
pv shows
/dev/sdc   VolGroup02   2.27T (size) 2.17T (free)
i want to extend the logical volume /dev/VolGroup02/u03 by 100gb
lvextend -r -L +100G /dev/VolGroup02/u03  dev/sdc
and is it necessary to unmount it first  ?                 
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