Partimage

Partimage
Partimage is a Linux utility which saves partitions having a supported filesystem to an image file. Most Linux and Windows filesystems are supported. The image file can be compressed with the gzip / bzip2 programs to save disk space, and they can be splitted into multiple files to be copied on CDs / DVDs, ... Partitions can also be saved across the network since version 0.6.0 using the partimage network support, or using Samba / NFS. If you don't want to install Partimage, you can download and burn SystemRescueCd. It's a livecd that allows to use Partimage immediately even if your computer has no operating system installed (useful to restore an image), and it allows to save an image on a DVD on the fly.
Partimage will only copy data from the used portions of the partition. For speed and efficiency, free blocks are not written to the image file. This is unlike the 'dd' command, which also copies empty blocks. Partimage also works for large, very full partitions. For example, a full 1 GB partition can be compressed with gzip down to 400MB.
This is very useful to save partitions to an image in some cases:
First you can restore your linux partition if there is a problem (virus, file system errors, manipulation error). When you have a problem, you just have to restore the partition, and after 10 minutes, you have the original partition. You can write the image to a CD-R if you don't want the image to use hard-disk space.
This utility can be used to install many identical computers. For example, if you buy 50 PCs, with the same hardware, and you want to install the same linux systems on all 50 PCs, you will save a lot of time. Indeed, you just have to install on the first PC and create an image from it. For the 49 others, you can use the image file and Partition Image's restore function.