There is no need to partition your hard drive.
- Take a complete backup of your hard disk.
- Reinstall Server.
- Use the Server.app program to create three web sites.
These sites will either need to be on three different ports at the same address (which is something you can do entirely by yourself) or need to be at three different host names (you'll need an agreement with a DNS host so that those addresses all point at your computer). You can set them up as three different ports first, so you can test them and get them working, then change to three different host names later once they're working.
Server.app runs fine on on an iMac box or Mac Pro or Mac Mini or Mac Mini Server.
I know folks that do this both ways. Dedicated servers, and servers that are sharing a host used for typical client activities.
The choice comes down to differences in management; servers are expected to be online all the time, and to seldom change configurations, and to be comparatively secured against remote attacks. You generally don't want your servers to drop offline, for instance.
Systems managed as clients can boot or crash or get reconfigured or reloaded or powered down, and that then only effects the local user of the client. Software installed or reconfigured on clients is also less of a problem, as remote folks aren't usually poking at the client box, both for typical access and while seeking weaknesses.
Security is another factor and another consideration, where remote access into your client is generally something only you and authorized folks on your local network might be doing. Servers are accessible to all, and get probed and get attacked very regularly. A web breach that gets extended could expose your files, for instance. Folks that are moderately paranoid will generally configure servers into a DMZ network, so they're isolated from the rest of your systems and your network should the system or the web server become breached.
There are some other minor issues, such as your server will also need to have a static IP address on your network, as any forwarding configured on your firewall will need a fixed target, and other hosts using Server for DNS services or such also want a static IP address.
If you're running a server, keeping it patched to current is more important, too. Both the OS X software, as well as any content management systems or tools you're running for those web sites...
Do also make sure you have good backups, as that's your path back from accidental file deletions, or from server breaches, etc.
The above is not intended to scare you, just to cause you to think about how you manage your client systems, and how you might want to manage servers, and what you might want to consider when managing and securing the client and the server systems.
Partitioning is not necessary.
Have it up and runnning. I did just what ( Simon Slavin) suggested just before I read your post and after much contemplation, so your post did solve my problem and reinforced my decisions. Thank you.
MrHoffman, food for thought! I'm a real newbie at OS X Server and website creation so you have given me more to consider, thank you.
I bought one of those OS X Server for dummies books and am trying to catch up with things asap.
I didn't partition, thank my lucky stars .