Windows Distributed File System (DFS) has been around for a
long time and it has always had a lot to offer. With the latest update in
Windows Server 2003 R2, DFS has become quite an impressive product.
At ORCS Web, we have recently started to use DFS for some of
our high availability offerings that use a central NAS (Network Attached
Storage) content server. We are using DFS for handling the content server,
both for replication and for automatic failover to a backup server in the event
of maintenance or a server failure.
There were a number of things that I learned while
researching, testing and rolling out DFS for WebFarm content hosting that I
will share here. This is not a step-by-step walkthrough, but rather some
pointers that you will hopefully find useful.
DFS has many usages ranging from keeping content in sync
between different physical sites, to giving a single easy-to-remember path that
can serve up content from a variety of folders across a local or wide area
network (thus the "distributed" in DFS).
DFS in its simplest form is a way to have a single friendly
UNC path on your network which can have folders distributed across multiple
servers. This friendly UNC path will be permanent while the real folders that
it accesses behind the scenes can be most anywhere. Subfolders can point to
completely different locations on disk or to different servers on your network.
This flexibility is great for our WebFarm situation and allows a primary and
at least one backup server to handle the content with a clean failover solution
in the event that the primary server fails.