Clustered install, Partitioning SAN drives?

[Diluted]

First, I need to know if my setup is feasible. I have two servers and both will run all of the Zimbra services except for LDAP, which is handled by the AD controller in my domain. I set up one server by itself and have it running with no problems. I'm using CentOS 5.

We are using an iSCSI target as our shared storage. I have a total of 200GB available for this project and I'm wondering what the best way to break it up is. I know I need separate storage area for each server, so that really limits me to around 100GB for each server. I'm not using the clustering feature as load balancing, but merely for redundancy in case of hardware failure. the current way I've broken up the 100GB for each server is:

conf: 100 MB
log: 250MB
redolog: 110MB
mysql: 2GB
store: All space left over out of 100GB... ~84GB, I think...
index: 5GB
backup:8GB
logger: 250MB

Does this seem reasonable?

Thanks!