Choosing a Disk-Cloning Solution for Your Nonprofit

This article was adapted from a forthcoming IT workbook created by TechSoup's MaintainIT Project, an effort funded by the Bill & Melinda Gates Foundation to gather and distribute stories around maintaining and supporting public computers.

Disk-cloning software, also known as disk-imaging software, is a time-saving program that creates a sector-by-sector, low-level copy of an entire hard drive (or partition). Disk-cloning automates the tedious task of installing an operating system and dozens of programs every time you get a new computer. It also saves you from repeating the entire setup process on those unfortunate occasions when a system crashes and needs to be rebuilt. Symantec Ghost and Acronis True Image are two well-known disk-cloning programs, but there are dozens of others to choose from.

What's the Difference Between Disk-Cloning Software and Backup Software?

Disk-cloning software is primarily meant to save you time and automate the routine work of installing operating systems and software, while backup software is intended to protect data files in case of a hard drive failure or other disaster. Disk-cloning programs do provide some incidental protection against data loss, but their main purpose is to capture a particular configuration of software and operating system. That snapshot can then be pushed out to another PC with similar hardware components (for example, similar motherboard, similar processor) or to dozens, or even hundreds, of PCs. Increasingly, disk-cloning programs offer you the ability to copy specific files and folders instead of an entire hard drive. In this way and others, they have more and more of the features that you'd expect to find in a backup program. However, disk-cloning applications still aren't appropriate for day-to-day backups of mission-critical data.

Six Ways Disk-Cloning Software Can Make Your Life Easier

1. 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 days, or even weeks, 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. However, keep in mind that for this solution to work, your computers must have similar hardware components. The motherboard and the processor need to be identical or at least similar. The hard drive on the destination machine needs to be as large as or larger than the hard drive of the source computer. If the video card, network card and so on aren't identical, you may be able to work with a single image, but there'll probably be some extra work involved. On the other hand, disk-cloning programs are getting better and better at handling hardware discrepancies between the source and destination machines, so you should consult your vendor to see how much leeway you have.

2. 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, it's almost guaranteed that each computer will be a little bit different. For more information, check out Tips for Standardizing Your IT Infrastructure.

3. Restoration of your computer after it fails:

   You should be backing up critical files on a daily basis or even more frequently, but having a reliable data backup is only the beginning of the recovery process. Over months and years, you've probably installed several dozen pieces of software and tweaked the settings in a hundred different ways. It could take you days to return your crashed computer to its original state. If you have a recent snapshot (for example, a recent disk image), you'll be up and running in an hour or so.

4. Preventive maintenance and troubleshooting:

   Some organizations don't wait for a complete hard drive failure. Instead, they use cloning software to fix relatively minor problems. The cloning process takes a few minutes to an hour, depending on the speed of your network, and you don't have to watch it as it runs. Overall, it's fairly predictable. On the other hand, you often have no idea how long it'll take to repair a problem with somebody's software. It could take minutes, or it could take days.

5. Training labs:

   Many organizations with training labs and public computers reimage these machines periodically to eliminate any developing problems, viruses, spyware, patron downloads, abandoned files, etc. Disk security programs, such as Windows SteadyState, Clean Slate, or Deep Freeze, have the same effect, but they use less bandwidth and fewer server resources.

6. Migrations and hard drive upgrades:

   If you're buying a new computer or putting a new hard drive into an existing computer, you can save your current configuration to a disk image file and then use that image to set up the new drive. Bear in mind, however, that the greater the hardware differences between the two computers, the more trouble you'll have with the migration if you use this technique.

What to Look for in a Cloning Solution

• Consumer or business:

  Symantec in particular sells a home version and an enterprise version of its imaging software. If you plan to image more than a small handful of computers, you should opt for the enterprise version, also known as the Ghost Solution Suite, which allows you to "multicast" (see below). The home version of the same product is simply called Norton Ghost.

• Maximum limits:

  What's the maximum number of computers that the software can handle simultaneously?

• Other software capabilities:

  • As mentioned previously, think about how the cloning software reacts to differences in hardware components.
  • Can you restore individual files from your disk image without restoring the entire disk? In other words, can you browse the image as though it were a file system and pull out a single file or a handful of files? With the current versions of most cloning programs, you can do this.
  • Will the software perform incremental or differential updates? In other words, will it scan your source computer for recent changes and incorporate only the changes into your master image file? Creating a full image can really hog your organization's network and computing resources. These small, incremental updates are much more efficient.

• Imaging assistance:

  Should you do the imaging yourself or pay a third party? Computer manufacturers, resellers and other companies are happy to clone your computers for a price. The larger your order, the more likely you can benefit from this type of arrangement. Cloning 50 or 100 computers at once can put a serious strain on your network and your IT department staffers.

What to Consider When Implementing a Cloning Solution

• Hardware purchases planning:

  For cloning to work effectively, you need to have a minimum number of different hardware models. 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. More is not better in this case. On the other hand, it's easier than it used to be to support several different models with a single image.

• Master disk images planning:

  Who creates the images? Who decides what software to include and how to configure that software? Remember, 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.

• Source image preparation:

  Microsoft Windows operating systems come with a utility called Sysprep that strips out all unique, specific information (for example, computer name and Security Identifier) from your source hard drive and gets it ready for cloning. NLite is an open-source program that lets you strip out Windows Media Player, Microsoft Outlook Express and other add-on features from Windows XP (but not Vista). These preparation utilities are often used in concert with post-cloning tools such as Ghostwalker. (See below for more details on these tools.)

• 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 may slow your network down somewhat (do it after hours or during non-peak hours), but it was designed specifically to send lots of information to lots of computers with the least possible overhead and bandwidth use. It won't choke your network as long as your network infrastructure is relatively up-to-date. Also, if you'll be cloning and multicasting on a regular basis, you should consider dedicating a server to the process.

• Testing:

  If you're cloning lots of computers, image one or two and examine them carefully before deploying to your entire 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.

• Post-cloning steps:

  Your computers might be 99 percent identical, but that last 1 percent is still important. After you've cloned your PCs, you need to change the name of each one to avoid conflicts on the network. If your computers use static IP addresses (increasingly rare), you should assign these manually to each machine after they're imaged. In a Windows domain environment, you also need to assign a special identifier (called an SID) to each machine. Often, your cloning software will have a tool that can handle these steps automatically (for example, Ghostwalker). Also, on Windows machines, Setup Manager (XP) and System Image Manager (Vista) can help you automate the post-cloning routine.

• Image storage and management:

  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 fantastic amounts 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.