Kurt Shintaku's Blog

File this under "Wow."

Some organizations create drive images that they use to build new desktops & servers with.  These drive images may need to be replicated across WANs to enable local sites to build systems with.

The problem is that historically, any change made to the drive image woud result in a massive "resyncing" of the replicated image files.  Because image files are often 8-20GB in size, this can result in a tremendous amount of traffic.

But not with Windows Server R2 DFS-Replication.  Using Windows Server R2’s "Distributed File System & Replication", it is possible to build a single virtual server name like "CORPIMAGES" that everyone in a worldwide network references – and each user is automatically directed to the file share "replica" that is nearest them geographically, so that local site users go to local file share replicas.

If a drive image is created using Windows Imaging Format (this is important), every time a drive image is modified/updated on the CORPIMAGES virtual share, only the differences are replicated to the file share replicas throughout the WAN network.  This results in a massive savings of time and bandwidth for a corporation.

How massive?  Our folks in Redmond did this exact test across two different drive images that resulted in a 91.59% reduction (151.59 MB replicated instead of 1.76 GB) in traffic and replicated data.  (Reference here)

What’s even more impressive is that the Windows Server R2 ENTERPRISE EDITION cross-file remote differential compression results in even less traffic being needed to be replicated.