Before you begin your Calendar Server deployment planning, a good question to ask is:
Why is my organization deploying Calendar Server?
Several reasons to consider are:
Cost savings. The total cost of ownership per user is lower than using other calendar products on the market.
Increased productivity. Your calendar users can manage their events and tasks as well as schedule meetings and appointments with others in the organization. Your users can also manage calendar groups and resources such as meeting rooms and equipment. They can also synchronize their calendars with mobile devices and Microsoft Outlook.
Improved scalability and availability. Calendar Server scales both horizontally and vertically. If your organization grows, you can easily upgrade your configuration by upgrading a server or add more servers.
High availability (HA) configuration. Integration with Sun Cluster software enables you to configure Calendar Server as a highly available service. If you experience a software or hardware failure, Calendar Server fails over to a secondary server.