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Desktop imaging lessons learned
Blog All software is designed to deal with a specific problem. In the case of the current set of articles that problem is desktop deployment.
If multiple different developers attempt to solve the same problem, then chances are good that they will run into the same obstacles. Different developers will have different approaches regarding overcoming these obstacles, and differing levels of success.
Some developers create workarounds so seamless that you only notice that an obstacle needed to be overcome in the most exceptional of circumstances. In other more unfortunate cases visible and ugly problems affect all software in a given field. This article will expand on some of these gotchas - both those endemic to individual desktop imaging applications, and those to which all desktop imaging apps fall prey.
In the previous articles on this subject I examined the desktop imaging applications PING (Partimage Is Not Ghost), Windows Deployment Services (WDS) and Symantec Ghost. Ghost was head and shoulders above the other offerings, with PING offering a rather lackluster showing for open source imaging applications. On the advice of a colleague, and wanting to give open source another go, I promised to take a look at both FOG (Free Open-source Ghost) and Clonezilla, having wrongfully neglected them in my implementation article.
Fog and Clonezilla both serve as fantastic examples of the two standard types of imaging options available, PXE multicast and boot CD. FOG is a PXE multicast solution: create an image, send it to the FOG server, and from there you can stream it to multiple target computers simultaneously.
Clonezilla is a boot CD: put it into a computer, boot from the CD, and you can make an image of that computer onto another hard drive, a flash drive or a network share. Alternately, you can boot from the Clonezilla CD and deploy an image to that computer. It is theoretically possible to use a PXE/TFTP setup to deploy Clonezilla in a manner that would allow it to run on multiple computers simultaneously, but frankly FOG just does it better.
Both Clonezilla and FOG do their jobs remarkably well; they are complimentary programs that in tandem offer all of the major features of either WDS or Symantec Ghost. While I don’t feel that either FOG or Clonezilla are of themselves a complete solution to the desktop imaging problem, combined they are a very serious challenger to Symantec Ghost, and a viable option for business desktop deployment in their own right. For those wanting to give FOG a try without the hassle of setting it up yourselves, a VMWare appliance is available. Clonezilla is available as a livecd.
As a server-based multicast imaging solution, FOG is designed to help systems administrators roll out collections of customised images to large numbers of desktops. As such, FOG is designed largely with corporate setups and demands in mind. One of the most notable features is that of partial Active Directory (AD) integration. FOG can be configured to rename any copies of Windows it deploys and join them to the domain. Fog does this by relying on the image it is deploying having the Windows Support Tools installed, specifically netdom.exe. Without it, any attempt to join the imaged computer to the domain will fail. Fog scales well, with real-world uses managing deployments to tens of thousands of computers.
Like any application though, FOG is not without its foibles, however they are very well documented in the site’s wiki. Be very certain to correctly tell FOG which operating system you are imaging. I have found it is far touchier about this than other imaging applications. As with WDS or Clonezilla, you will need to Sysprep systems before you image them, there is no built-in SID regenerator.
Ghost on the other hand does have an SID regenerator built in. You can configure your multicast sessions such that a given image has its SID wiped on the fly during deployment. Ghost is packed full of these sorts of features, faced with heavy competition from all corners, adding features is the only way to survive. When you buy Ghost you are buying not only the features but the constant updates and bug fixes.
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