According to the install docs i'm supposed to configure /boot and swap then use the remaining for /root. I really don't want to do this and would like to know exactly which mount point is the most important for storage.

A quick google search indicates /opt/zimbra is where the message store goes so my question then is are there any other important directories that need a lot of space?

my plan is:

100m /boot
8gb swap
20gb /root

then with the remaining 700gb i would mount to /opt unless there is some other directory that also will require a lot of space.

If /opt is the only thing that eats space please let me know so i can go forward with this install.