PHDs aren't Network Home Directories
We've had portable home directories in BSD Unix long before Apple adopted Unix. You don't need "Server". I remember having a "512K mac" with no hard drive at the same time as also having a Sun Workstation running a BSD derived OS. At that that my files in the home directory would follow me to whatever machine I logged into.
All you need is to run the automouter on all your clients so that when users log in their home directory is mounted. The size of the client hard drive does not matter if the user data stays on the file server.
You're talking about Networked Home Directories. PHD is different than mounting a home directory via NFS, SMB, AFP or whatever.
PHDs are portable. It's a synchronization of your files between a local home directory and a fileserver. With a PHD, you work locally instead of over the wire, and your changes are pushed/pulled down regularly. Some 'chatty' apps like Safari run just terribly with a network home directory because it's writing caches, history.. lots of stuff, all the time.
PHDs are like IMAP mail. You mirror the content on the server and the client. You can disconnect your laptop and you've still got your 'stuff' while you're on the airplane.
Windows offers the same functionality and it's nicer in some ways (live background updates as you modify files).
Yes, you can have a PHD where the local and remote home directory are different sizes.
You can apply rules to synchronization. By default, caches and such are ignored. It's a good idea to ignore the user's Mail directory because it's always changing and Apple's Mail.app stores each mail as a separate file.
You can write custom rules.. like don't sync any folder with "nosync" in the name. You can have your users put personal movies in ~/Movies/nosync/ or in ~/Movies/movies that are nosync/
I have a low use PHD setup where the clients know they're Guinea Pigs. I ignore most of ~/Library/ as well as ~/Music/iTunes/ ~/Documents/Parallels/ and so on.
You want to ignore monolithic stuff like Parallels or VMWare drive images.
You might want to ignore the Downloads folder
You want to ignore anything that is machine specific (some stuff in your library)
You want to ignore stuff that doesn't need to be synced.. like IMAP mail (since IMAP is designed to sync on it's own (between client and mail server)).
I'm just getting ready to roll out a large 10.5 PHD system. I've been waiting on AD fixes in 10.5 and I'm ready to go.
Clients will sync with a fileserver (XSAN volume). The Web Server will have access to the XSAN so users can edit their personal website on their local hard drive and it will auto-magically update their real website with each sync. Files will be available from several locations via PHD syncing to multiple machines, network home directories, or file serving.
I have one Prof who syncs his office desktop with his home desktop. He works at home.. syncs.. then his work is waiting at work.
Almost forgot.
10.5 Server can track PHD changes on the server side. The PHD client is tied into the filesystem so it knows exactly which files have been written (created, modified..) and it only syncs those files. 10.4 used to scan the filesystems and it took a while and hit the drives noticeably.
ffakr.