Computer cloning, or ghosting as it is sometimes called, involves setting up the operating system, drivers, software, and patches on a single computer, then automatically replicating this same setup on other computers using specialized software. It is sometimes referred to as imaging as well, as the configuration dataset is called an "image." Depending on the type of software you use, cloning can be done using a disk or other media, or over a network. Cloning allows you to efficiently set up multiple computers, and can be done at any charity or organization where you want to ensure that every workstation is configured the same way and with the same software.
The Advantages of Cloning
There are obvious reasons to clone computers in a community technology center (CTC), but cloning can also be a huge help for any organization that needs to configure multiple computers at once. Setting up just one workstation manually can take anywhere from a couple of hours to an entire day; deploying an image on the same machine, in contrast, takes much less time. Cloning can even be advantageous for a standalone machine that's not on a network, for the following reasons:
- Standardization. When you use disk cloning, you ensure that your computers are as close to identical as possible. If you do each installation and configuration individually, each computer will end up being slightly different. Managing standard machines is a lot easier than disparate ones.
- Training labs. Many charities and organizations with training labs and public computers re-image these machines periodically to eliminate any developing problems, viruses, spyware, user downloads, abandoned files, and so on. This ensures that the user experience at your lab will be the same for all users.
- New computer staging and deployment. If you buy a batch of new computers and you want to install a specially configured, unique combination of software and operating system, cloning software can save you a lot of effort. Install the operating system and the software on your source machine, tweak all the settings, and then the cloning software copies that disk image to all of your destination machines.
Disk images are primarily meant to save you time and automate the routine work of installing operating systems and software. Disk-cloning programs can provide some incidental protection against data loss, but their main purpose is to capture a particular configuration of software and operating system. This means cloning software isn't appropriate for day-to-day backups of mission-critical data. You should rely on dedicated backup software to protect data files in case of a hard- drive failure or other disaster.
Major Considerations Before You Begin
Keep in mind that the machines you clone must all use the same operating system. While cloning can be performed for any platform, Mac clones won't work on PCs, Linux clones won't work on Macs, and so forth. That said, the following are some considerations to get started:
- Hardware purchases planning. For cloning to work effectively, you need to have a minimum number of the same hardware for the same image. If you buy a few computers here and there, you'll wind up with a patchwork environment, and you'll have to manage dozens of different disk images. Having m ore models is not better in this case.
- Similar hardware components. Disk-cloning programs are getting better at handling hardware discrepancies between the source and destination machines, but you should consult your vendor to see how much variance your setup would allow.
- Master disk images planning. If you don't have dedicated IT staff, determine who creates the images. This can be an involved process, so make sure your non- IT staff has the availability to do this. In addition, you need to figure out who decides what software to install. These disk images may be deployed to dozens of staff computers or public computers, so the affected parties should have a voice in the development of the image.
- Image deployment. You can always perform a direct disk-to-disk copy of an image. In other words, your source and destination hard drives are connected to the same computer, or they're connected via a network. The transfer is direct, without any intermediate steps. However, many systems administrators create a "master image" and then deploy from that. The master image is usually stored on a removable hard drive or a network drive. When you have a large number of computers to image, you should consider deploying the image across the network. Using a technology known as multicasting, enterprise-level disk-cloning programs can image dozens of computers at the same time. Multicasting was designed specifically to send lots of information to lots of computers with the least possible overhead and bandwidth use. If you plan on doing cloning and multicasting on a regular basis, you should consider dedicating a server to the process.
Using Cloning Software
If you're cloning lots of computers, image one or two and examine them carefully before deploying to your entire charity or organization. Check that your image is reliable and uncorrupted. Also, look again to make sure that you haven't forgotten an important setting or an important piece of software. Remember that any mistake you make will be replicated across a large batch of machines. In some cases, you might want to image your computers in waves.
As you formalize your cloning policy and strategy, you will also need to figure out how to store and manage these different images. With most cloning software, you can save your images to a local hard drive, a network drive, a tape backup, CDs, or DVDs. Avoid CDs and DVDs if you can. Since most images won't fit on a single CD or DVD, you'll have to span your image across multiple disks. However, once you've saved your master image to a local hard drive or a network drive, you can use DVDs to create backups of these images.
If you support a large number of computers, disk-cloning software can save you a lot of time. However, plan carefully before you commit yourself to a particular solution, and test thoroughly before you re-image a large batch of computers.
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