In my career, I have managed the deployment of Macintosh labs and offices in colleges and elementary schools and at companies with a few workstations and at major corporations. In handling most large-scale deployments or software upgrades, the most efficient solution is to use imaging, which places the contents of a master disk image on the hard drive of each workstation or computer. Creating and deploying a master image -- whether you're installing new computers, restoring computers to a default state or providing a massive system upgrade -- can be a major task for any IT department.
In the PC world, Symantec Corp. offers an excellent product called Ghost. It's a simple, server-based product that allows administrators to create disk images from a model PC, boot workstations from a floppy and replace the workstation hard drives with the image on the Ghost server. It requires very little user interaction, and dozens of machines can be imaged at a time with little intervention. Although there is no Mac version of Ghost, there are a number of Mac OS X options that provide similar results.
Apple Software Restore
Before Mac OS X, Apple provided a graphical tool called Apple Software Restore (ASR) that could be used to image a hard drive. To use ASR, a master image is created with Apple's Disk Copy utility and then two special scripts are run on it from within Disk Copy to prepare it for use. The image is then placed in a folder called Configurations in the same folder as ASR. The parent ASR folder can be stored on a file server or placed on an external hard drive or removable disk (including a CD or DVD). Workstations being imaged must be booted from an alternate disk from the hard drive receiving the image. Generally, this requires technicians or administrators to create a custom-bootable CD with the needed version of Mac OS 9 and drivers to boot the computer and access the ASR folder.
Although the graphical user interface (GUI) version of Apple Software Restore can be used to deploy a Mac OS X image, the computer receiving the image needs to be booted in Mac OS 9 to run Apple Software Restore. Since almost all Macs introduced after December 2002 no longer boot into Mac OS 9 (recent iBooks being the exception), this tool's effectiveness is limited. Although a Unix command-line version of ASR is included with recent Mac OS X updates, it can be cumbersome and may require more time at each workstation than older versions of ASR. The only available documentation on the command-line version of ASR can be found in the Unix manual pages by typing "man asr" in Mac OS X Terminal application.
Details on the GUI version of ASR are available online.
Mac OS X Server's NetInstall
With Mac OS X Server version 10.2, Apple introduced a feature called NetInstall. Based on OS X Server's NetBoot technology, NetInstall allows a number of Macintosh models to boot from an image on the server and then run through the Mac OS X installer without actual installation CDs. NetInstall allows Mac OS X update packages to be installed in the same manner and is designed to let administrators create installer packages for individual applications and customize the Mac OS X install process.
NetInstall provides a good tool for upgrading earlier Mac OS machines that support NetBoot. However, the more I've tried to use NetInstall and the more I've heard about it from fellow Mac OS X Server administrators, the less useful I've found it to be. It only offers installation capabilities, and while it allows you to customize the installation to some degree, it doesn't offer the full machine-imaging features of other technologies. The process for creating custom packages for additional applications is cumbersome and can be learned only through trial and error. (Documentation for NetInstall is painfully lacking in both Apple's online knowledge base and the PDF "Admin Guide" that accompanies Mac OS X Server). I've also heard from a number of people that modifying the basic install process caused installations to fail.
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Ryan Faas has been an IT professional and technology writer specializing in Macintosh for nearly 10 years. Currently managing the Mac OS X Server and Macintosh workstations for a community college in upstate New York, he has deployed, administered and trained users in Mac and mixed network installations in institutions ranging from small graphic-design firms and school districts to major media companies. He is also co-author of Troubleshooting, Maintaining and Repairing Macs (McGraw-Hill Osborne Media; 2000). |
Apple's NetBoot and Apple Remote Desktop technologies provide better ways to get the same results. NetBoot can be used as a start-up disk, and Remote Desktop 1.2 provides the ability to install update both operating system and application packages remotely (see story)
Bombich Software's Carbon Copy Cloner and NetRestore
Perhaps the best imaging product on the market for imaging modern Mac installations are the shareware tools Carbon Copy Cloner and NetRestore from Bombich Software. The first of these tools, Carbon Copy Cloner, is designed to simply clone a hard drive or other mass-storage device, creating an exact duplicate on another drive or an empty disk image. Files, permissions and directory structures are all replicated, providing a simple tool for creating master images. By itself, Carbon Copy Cloner can be used with a portable drive, such as an external FireWire hard drive, to image a small lab or office environment. Its primary limitation is that it functions only when run on devices connected locally, not over a network.
NetRestore extends the ease of use Carbon Copy Cloner with the ability to perform restores from disk images shared using the Apple File Protocol (such as used in a Mac network) or HTTP, which offers more options for hosting master image files. It can also restore from local disks or disk images. In addition to network support, NetRestore contains several options for automating the process and can perform some postrestore actions, making it the most versatile tool I've seen for imaging tasks.
In addition, NetRestore comes with a tool to convert an Apple NetInstall image for use as a boot disk. With this option and NetInstall on a Mac OS X Server, it's possible to NetBoot client computers from the image and automatically run NetRestore in a fully automated mode that reboots when complete. A technician or administrator need only hold the "N" key at start-up on each workstation to set that workstation to search for a NetBoot server in order to image an entire company. When large numbers of computers require a single image with limited differentiation after imaging, the use of Carbon Copy Cloner, NetBoot and NetRestore can drastically reduce the overhead of deployments or mass upgrades.
Dantz Development Corp.'s Retrospect
Retrospect is truly designed as a backup tool. Most institutions will use it solely to back up their Mac OS X Server units and a few critical workstations. However, the server version's ability to backup and restore workstations can make it a usable tool for imaging individual computers.
Retrospect provides one advantage over other tools. Because it's a backup product, it can replace only selected or changed files when imaging a computer. This works if you want to implement a new image without having to store work on the workstations while they're being imaged. It's also helpful in situations where computers need to be re-imaged because of a software problem. Often, it's capable of creating an image and deploying it to a single workstation much faster than other options.
To reiterate, Retrospect is primarily a backup solution, which means it has certain limitations that will affect its use in environments where more than a handful of computers need to be imaged. The predominant limitation is that Retrospect is capable of only imaging (or more accurately, restoring) one workstation at a time. This can be acceptable in a small deployment (such as an office with fewer than a dozen users, where the same version of Retrospect can later be used to provide backups of individual workstations). But using it in larger deployments can be time-consuming.
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