storedge 3510 configuration - unmapped partitions

[Bert Hutzler]

my raid 1 consists of 24 140GB disks, which were configured by my predecessor as follows:
one logical drive 0
four partitions:
partition 0: 150GB
partition 1: 40GB
partition 2: 30GB
partition 3: the remaining aproximately 1.4TB, which is unmapped (no host LUN asignment)
1. this configuration looks not very meaningful to me and i have no idea why he didi it this way.
2. we're running database devices mainly on the 150GB partition and are now running out of space (what's rather ridiculous with 1.4TB of unassigned space)
3. how can i make available this untapped capacity if possible on the fly without any interruption?
i'd like to change the size of partition 3 to another 150GB getting the rest as free space. but the documentation says, doing that i first have to unmap all assigned LUNs. is that true or could i do it without unassigning the other LUNs? if not, is it possible to just assign partition 3 as a whole to the host and this way use the 1.4TB?

thanks in advance for any help
Bert