Which Duplication Method Is Right For You?
By Jonathan Feldman
Identically configured network-connected computers are a necessity for harried network administrators and technical support staff. Whether you use network computers (NCs) or PCs, standard desktops are a godsend--especially for those who staff the helpdesk.
If you use PCs that boot from an internal drive, duplicating those drives can save hundreds of hours, especially if you're using Microsoft Windows95 or Windows NT (for reasons we'll explain later). Only a year ago it was hard to find software to duplicate these drives, but as Win95 and NT took up more corporate real estate, more solutions arrived.
We tested three software-based hard drive duplicator package
s: Binary Research's Ghost, Corporate Systems Center's Dupe-IT and HDCP, a shareware package. Ghost was the most flexible--and expensive--of the three; Dupe-IT lets you duplicate an arb
itrary number of physical drive targets at once; and HDCP is small, fast and inexpensive. Each of these duplicators is DOS-based; Dupe-IT offers a Windows95 and NT executable as well.
Duplication Invitation
There is a pressing reason to duplicate rather than run installs: time. Whether you use the "push" installations that are detailed in Microsoft literature or install from CD-ROM, it takes much more time to set up a hard drive than to clone, or duplicate, it. Setup programs are not optimized for speed; duplicators are.
This problem also is present in the DOS/Windows 3.x world, but it's surmountable with any of the various file copy or archive utilities available, such as PKZIP. As new setups are necessary, a technician simply copies an archive from a network drive to a freshly formatted hard drive. This method
isn't optimal, because the additional steps of FDISK and FORMAT are involved and network user profiles don't exist, but it works.
Loading hard drives with a standard configuration also simplifies troubleshooting. You don't have to worry about version control or the interoperability of 800 different Dynamic Link Libraries (DLLs). If a workstation is misbehaving, you can install a "known good" image onto it.
With the addition of long file names and the registry, Windows95 and NT have made it difficult to duplicate hard drive setups in the same way. Although a Microsoft Corp. TechNet article details a method of "image download" using XCOPY32 and LFNBACK, this method involves many points of intervention, requires a reasonable amount of savvy from the technician, and does not address the problem of duplicating NT File System (NTFS) partitions.
Disk duplicators are a simple, one-step solution. For example, in our environment, a technician uses only a Novell boot disk to set up and configure a row of machi
nes. The tech simply boots each system, logs into the network and runs a duplicator, which populates each hard drive with a Windows95 or NT image. The technician can walk away once each transf
er is initiated and come back in less than an hour to fully configured workstations.
Of Drives and Dupes
Deciding which hard drive duplication method to use requires understanding a couple of things. Most important is knowledge of physical (drive-level) versus logical (in most cases, FAT-level) drive copying (see "Physical Versus Logical Copying" diagram).
In logical copying (or partition copying), only the data from the partition is copied. The downside is that you need to manually FDISK and FORMAT each and every hard drive. This becomes a waste of time when performing many duplications, but it's acceptable when only performing a few. The upside of logical copying is that you get an image that is exactly the size of the data, not the drive. So,
a 2-GB drive with 500 MB of data would produce a 500-MB image, which would fit nicely onto a CD-Recordable (CD-R) disc. We usually produce a permanent image for archival purposes when we've completed a project.
In physical copying, the entire contents of the drive are copied, regardless of how much data is on it. This makes for very large image files, because the empty space is also copied. That same 2-GB drive with 500 MB of data will produce a 2-GB image. Additionally, physical copiers reproduce the entire partition table, so a source drive with a 500-MB partition copied to a 2-GB drive would waste 1.5 GB of space.
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