Take a look at David Knipe´s VPP Sync project. I´ve used it in the past with great success.
Hope this helps
You can store the vpp directories in a shared directory e.g. on the db server. And in EPiServer.config specify an network address like \\10.3.1.1\MySharedFolder\Documents\. The application needs modify rights to the vpp directories, so run the application pool under a domain account.
You could also try DFS Replication. It seems to work fine.
We wanted the same setup and in the end we're going for 2 databases behind the load balanced web servers because we couldn't get around the caching issue.
Your destination server will receive a mirroring package and trigger a cache refresh. The second server will get the updated database and VPP (via replication) but its cache won't get refreshed. This causes inconsistency between two load balanced servers.
I am setting up a load balanced enironment for the EPiserver CMS 6 R2. There are two web servers and only 1 db server. I want to know what is the best way to synchronise the VPP folder to share assets between the two web servers. You help is much appreciated.