I have never had to create such a large lv before and it is giving me grief. Do I have to change the settings (PE's, etc) when I create the volume group?
When you create a new volume group you should start with the biggest disk. The PE parameter will be fine. It is not possible to alter the PE parameter once the vg is created.
A logical volume can be created across multiple disks in the volume group.
18GB's in not a large LVOL at all. Typically the problem you encounter is that the LVOL is mirrored and there are not enough PE's left on separate physical drives to allow the LVOL to be built. Another one is that the LVOL is specfied to be contiguous but there are not enough free extents in the right place to allow this. I am making the assumption that you have 18GB bit a bit more free space in the VG (or 36GB if mirrored once).
Without any other information, I would say no, just use lvcreate and newfs:
L=# lvcreate -L 18432 -n /dev/vg??
# newfs -F vxfs /dev/vg??/rlvol?
assuming you have the space on the volume group, otherwise you may have to add another disk to the vg. After this you will want to mount it and add the entry to the fstab so it will mount at boot time. Also, if you feel uncomfortable with the command ling, you can use sam.
At the vgcreate level, give the max PE peer PV to 5000 (-e 5000)to manage disk upto 20GB. Note the the VG limit will be 256 GB with an 4MB PE size. You can also change the PE size to 8 or 16 MB to allow futur extension. Note that the major parameter are at the VG level.
