crfs will create a JFS/JFS2 file system as well as the logica volume associated whereas mkfs will create a File System ove an already created Logical Volume.
crfs Adds a file system. The smallest file system is equal to on PP.
crfs -v jfs -g datavg -a size=32M -m /user : creates a JFS of 3 MB with /user as the mount point in VG datavg.
crfs -v jfs2 -g rootvg -a size=128M -m /data -A yes -p rw - agblksize=2048 : creates a JFS2 of 128 MB with /data as th mount point, automatically mounted at system restart (-A), wit 4K as the smallest file system block size that can be allocate to a file.
mkfs Makes a new file system on a specified existing devic (LV).
mkfs -s 64M /data /dev/lvdata : creates an empty 64 MB fil system on LV lvdata.
mkfs -o name=/user /dev/lvuser : creates an empty file system o the /dev/lvuser device, with mount point /user. The new fil system occupies the entire device and has the default fragmen size (4096 bytes) and the default nbpi ratio (4096).
