I have updated the description of the -l option of lvcreate to reflect the updated man page in the RHEL 7.3 draft. The description now begins with this paragraph:
"You can use the -l argument of the lvcreate command to specify the size of the logical volume in extents. You can also use this argument to specify the percentage of of the size of a related volume group, logical volume, or set of physical volumes. The suffix %VG denotes the total size of the volume group, the suffix %FREE the remaining free space in the volume group, and the suffix %PVS the free space in the specified physical volumes. For a snapshot, the size can be expressed as a percentage of the total size of the origin logical volume with the suffix %ORIGIN (100%ORIGIN provides space for the whole origin). When expressed as a percentage, the size defines an upper limit for the number of logical extents in the new logical volume. The pre‐ cise number of logical extents in the new LV is not determined until the command has completed. "
The examples remain the same:
The following command creates a logical volume called mylv that uses 60% of the total space in volume group testvg.
# lvcreate -l 60%VG -n mylv testvg
The following command creates a logical volume called yourlv that uses all of the unallocated space in the volume group testvg.
# lvcreate -l 100%FREE -n yourlv testvg
This can be seen in this document, section 4.4.1:
http://jenkinscat.gsslab.pnq.redhat.com:8080/job/doc-Red_Hat_Enterprise_Linux-7-Logical_Volume_Manager_Administration%20%28html-single%29/lastSuccessfulBuild/artifact/tmp/en-US/html-single/index.html#create_linear_volumes