# parted /dev/sdb (parted) mklabel gpt (parted) mkpart primary 0 2.5T (parted) quit
# pvcreate /dev/sdb1
You can also skip the first part and do:
# pvcreate /dev/sdb
You don't really need partitions. If you will use the entire disk for one single VG, then just use the entire disk :)