Virtualization

As with clustering and storage-area network (SAN) support, Leopard's support for server virtualization is limited to certain Windows Server Enterprise editions and above. In a change from its previous antivirtualization approach, Apple's end-user license agreement for Leopard Server does permit virtualization. Since this news is so recent, tools to actually implement virtualization under Leopard Server aren't yet available. VMware and Parallels have both indicated interest in developing such tools.

Both VMware Fusion and Parallels Desktop can run server and client operating systems, though the current focus of both products has primarily been on virtualizing client systems, including Windows XP and Vista. This means that, at the moment, you can theoretically virtualize one or more instances of Windows Server or any other platform on Mac OS X Server. So there are some significant virtualization possibilities already. In particular, this allows you to have the benefits of Mac OS X Server and Windows Server on one machine, which could be useful if you're looking to roll out a multiplatform environment.

Prior to Leopard Server's release, Parallels had begun developing a server-specific virtualization package for Mac OS X Server, and it seems likely that this package will eventually include support for virtualizing Leopard Server along with other server operating systems. This will significantly expand the virtualization options for Leopard Server. At the moment, however, virtualization tools for Leopard Server have yet to reach the breadth of what is available for other server platforms.

Which server is best for small business?

Small businesses form a unique market in the IT sector. They often need the features of a server platform but do not have the budgets to employ a full IT staff -- or any IT staff in many cases. They also need a solution that will support future growth. For this market, Microsoft ships a lower-cost version of Windows Server known as Windows Small Business Server that includes many Windows Server features, including Active Directory and Exchange.

While this is adequate for many businesses, the product has some distinct limitations for future growth. Active Directory support is limited in that only a single domain controller is supported with no replication options. That domain controller can't establish trusts with other domains, essentially limiting an organization to a single domain.

If an organization starts with or grows to multiple sites, the lack of replication means that every user log-in -- or other Active Directory query -- must be process across the network links between sites, often at the cost of slow performance and network congestion. Larger numbers of users can also result in decreased performance, even at a single site. (Microsoft suggests that Small Business Server is appropriate for organizations of up to about 75 users.) It also relies on a separate client-licensing method from other Windows Server products and typically has a limit to the maximum number of CALs allowed. When an organization outgrows Windows Small Business Server, it can purchase a transition kit to upgrade to one of the other Windows Server versions.

Mac OS X Server's unlimited client version may actually be more expensive than an initial Windows Small Business Server purchase, depending on the number of CALs. However, it provides organizations with significantly more room to grow. There is no limit to the number of users or for replication to additional servers.

More importantly, Apple has designed Leopard Server specifically for smaller organizations that have little or no IT staffers. The product features a simplified setup process that entry-level technicians or power users can master. It also has a very simple management tool known as Server Preferences, with an interface borrowed from Mac OS X's System Preferences utility.