Steps to create a new linux filesystem in a VMWare image

extend physical disk in vmware
create new partition on unallocated portion (fdisk /dev/sda, (n)ew primary partition, create on partition (2), (w)rite and exit
mkdir /opt/oracle/product/oradata2
reboot machine
create filesystem on new partition (mke2fs /dev/sda2)
add entry to /etc/fstab to mount the new partition on /dev/sda2 on /opt/oracle/product/oradata2 - for example:

/dev/sda2 /opt/oracle/product/oradata2 ext2 defaults 0 1

type 'mount' (or reboot)
create new oracle medium tablespace datafile on new filesystem

BTW the manual command to mount is:
mount -t ext2 /dev/sda2 /opt/oracle/product/oradata2