Disk Cloning - History

History

Before Windows 95, some computer manufacturers used hardware disk copying machines to copy software. This had the disadvantages of copying not just the used data on the disk, but also unused sectors, as the hardware used was not aware of the structures on the disks. A larger hard disk could not be copied to a smaller one, and copying a smaller one to a larger left the remaining space on the new disk unused. The two disks required identical geometries.

Other manufacturers and companies partitioned and formatted disks manually, then used file copy utilities or archiving utilities, such as tar or zip to copy files. It is not sufficient simply to copy all files from one disk to another, because there are special boot files or boot tracks which must be specifically placed for an operating system to run, so additional manual steps were required.

Windows 95 compounded the problems because it was larger than earlier popular operating systems, and thus took more time to install. The long filenames added to the FAT filesystem by Microsoft in Windows 95 were not supported by most copy programs, and the introduction of the FAT32 filesystem in 1997 caused problems for others. The growth of the personal computer market at this time also made a more efficient solution desirable.

Ghost was introduced in 1996 by Binary Research. It initially supported only FAT filesystems directly, but it could copy but not resize other filesystems by performing a sector copy on them. Ghost added support for the NTFS filesystem later that year, and also provided a program to change the Security Identifier (SID) which made Windows NT systems distinguishable from each other. Support for the ext2 filesystem was added in 1999.

Competitors to Ghost soon arose, and a features war has carried on to the present day. Many disk cloning programs now offer features which go beyond simple disk cloning, such as asset management and user settings migration.

On UNIX based computer systems, dd was more commonplace due to the lack of filesystem support in Ghost.

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