Well there are various ways to more-or-less achieve that result.
The ways that ABSOLUTELY keep the disk storage TOTALLY in sync between multiple PCs aren't that commonly used in a small scale / home environment. You'd be looking at something like a SAN or whatever so the disk storage is out on the network and isn't under direct control of EITHER of the PCs, for instance.
The problem with absolutely shared disk data is whenever EITHER of the PCs gets some malware or has a software crash, then ANY of the PCs can cause disk data loss / corruption that would then of course ALSO affect the other PC.
On the other hand if you just had the PCs be sort of independent with distinct hard discs, etc. and ran a backup / SYNC type program to keep most of the important aspects of the data on each one backed up and synchronized to the other periodically, you'd have some backup type of protection against something that corrupts data on one PC not immediately affecting the usability of the other PC. Of course that's also the downside, there's the possibility that there could be some period of time when one PC has new data on it but it isn't synchronized to the other PC before the first PC crashes or whatever, and the fail-over / synchronization has caused a bit of lost data.
Check these out:
http://allwaysync.com/
http://jonathanstoolbar.blogsp...7/27-sync-or-swim.html
http://www.microsoft.com/downl...92d8c52&DisplayLang=en
http://en.wikipedia.org/wiki/File_synchronization
http://www.karenware.com/powertools/ptreplicator.asp
Of course you can use more backup oriented programs as well to do things like
image backups of your drives total contents and then incremental backups off
of those etc.
Another possibility is to set up a 3rd computer which is a "file server" which the other PCs are just "clients" of, so if you login from either one of the client computers, your personal user account related information is shared to whichever PC you login from, and all of the other files / programs on the file server are also available to you on whichever PC you login from. You can even boot the workstation/client PCs over the network without them having to have disk drives at all in some cases.
That doesn't really solve a redundancy need for the data itself, though, since then what happens if your file server breaks? You'd need a redundant one of those, though that is usually easy to setup. Then you have workstation redundancy and server redundancy, but you'll have at least 3 PCs and one available spare for that to totally work....
