Setting up Zimbra Collaboration Suite high available

My current work wants to integrate Zimbra as a replacement for Novell Groupwise.
I did some research in setting up Zimbra in a high available mode, using CentOS, OCFS2 (on SAN), Heartbeat 2 and Mon.
In attachment you'll find a guideline and rationale for setting this up. Note that you need to register to download the PDF.
Please feel free to submit feedback about this procedure.
