Sample /etc/fstab file for mounting a second volume with a single partition and multiple entry points. That way you don't have to worry about statically allocated partition sizes.

fstab

# /etc/fstab: static file system information.
#
# <file system> <mount point>   <type>  <options>       <dump>  <pass>

proc    /proc   proc    nodev,noexec,nosuid 0   0
#Entry for /dev/sda2 :
UUID=9985b8e0-c4d9-45b0-8ae5-5c2edf16186b   /   ext4    errors=remount-ro   0   1
#Entry for /dev/sda5 :
UUID=70205578-8c03-42c9-9d7c-18c5755550ca   none    swap    sw  0   0

# Entry for second drive. (Large Partition)
UUID=fbb106e3-69ae-4b20-8e08-27fe45b901af   /storage    ext4    nodev,nosuid    0   2

# Directory binding options
/storage/var              /var          none    defaults,bind    0 0
/storage/home             /home         none    defaults,bind    0 0
/storage/srv              /srv          none    defaults,bind    0 0