It may sound odd offering more Zimbra installation advice since there is a lot on the subject in other blogs, our documents, wiki and Forums. In fact, some quick research surfaced over 1.4 million hits for Zimbra server install on the web and 36,000 on the Zimbra site alone.
But we are also fortunate to have more new Zimbra users than ever, and after helping some trial customers recently, it was a good reminder a few simple tips can help cut through some noise and avoid time-consuming snags once you start the install process. So without further ado here are the top 6 common pre-requisites to consider when preparing for your Zimbra installation:
1. Firewall
Servers have firewalls configured once the operating systems are installed for security purposes. Our recommendation is to temporarily disable the firewall on the system during a single and multi-server Zimbra installation. An alternative would be to refer to our installation guide to get a list of ports (see Table 1) used by the application and make sure the ports are open prior to installation. 
2. DNS setup
All Zimbra configurations store hostnames. We do not have save any IP address information in our configuration. The advantage is this allows an administrator to change IP address (more likely) on the Zimbra system without having to perform any application changes.
This scenario means that all the hostnames to be used in a Zimbra installation have to be defined in DNS. Both A and Mx records for the hostnames and email domains need to be defined and verified prior to beginning your installation.
One other thing to consider is split DNS configuration if you are dealing with servers separated by a firewall.
3. Use of Fully Qualified Hostnames (FQDN)
It is crucial to use a Fully Qualified hostname during the Zimbra configuration. For example, you should enter server1.domain.com instead of server1. This avoids incorrect DNS address lookups and ensures that the client would be connecting to the right application.
4. Port Conflicts
Standard server configuration comes with support for numerous services like POP, IMAP and HTTP (see Table 1). These services are also installed with the Zimbra Network Edition. Therefore, you want to make sure you disable all these services prior to installation. The Zimbra installation scripts will check for any of these port conflicts and notify you to turn these services off before continuing.
5. Libraries and additional packages
Zimbra’s rich feature sets are dependent on additional packages being installed on the system. These packages vary between Linux and Mac Operating system. The Zimbra installation script does perform checks to verify all the dependencies have been met, but going through the System Requirements documentation (available on the Zimbra website) before will save you some time.
STORAGE CALCULATION EXAMPLE
(Based on ‘Mailbox Usage of 200 MB’ and 500 users)
+ User Data: 500 users with 200 MB = 100 GB user data
+ MySQL data: 5% of 100 GB (User Data): 5 GB
+ Zimbra binaries: 10 GB
+ Zimbra logs: 20 GB
+ Zimbra indexes: 25% of 100GB (User Data) = 25 GB
SUBTOTAL: 100 + 5 + 10 + 20 + 25 = 160 GB
Backups: 160 % of Subtotal: 160 * 160% = 256 GB for backups
TOTAL: 160 + 256 = 416 GB
6. Sizing
Storage sizing is important for an excellent performing Zimbra application (see example). If you are doing a Network Edition trial you should contact the Zimbra technical team for sizing information for storage including number of disks, which Raid level to use, and the size of the drives to use. Configuration of the Zimbra store volume is important in satisfying the application IO requirements.
Remember, it’s also a good idea to review the Zimbra Quick Installation Guide where you can find this information and many more good tips.
Do you have a good tip to share? Feel free to add a comment!
Anup Patwardhan is the lead Zimbra sales engineer