Unable to reduce the size of volume group?

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http://www.linuxquestions.org – Step1: I have 3 lvm enabled partitions with sizes 300M,200M,100M. Step2: I converted them into physical volumes. Step3: I made volume group(VG) out of those physical volumes i.e, total size of VG is 600M Step4: I created a logical volume of 100M under the (VG) volume group. ---------------------------------------------------- Now the volume left under the VG is 500M Q:I want reduce the size of VG by 300M(500M-300M). Please tell me the necessary commands and required explaination. (HowTos)