There are many tools for this task both commercial and open-source / free.
My favorite is DBAN
For filesystem level, i.e. to securely wipe individual files or folders, consider Shred or Wipe
Imaging & Cloning
This client/server application allows you to backup partitions over the network. I have used it a few times and consider it a useful tool for bare-metal restores. It won't play nice with LVM though. Doesn't appear to be actively maintained. The partitions need to be unmounted, so you might as well reboot with System Rescue CD and use the partimage client from that.
Also, I have encountered various strange error messages about version mismatches. I was only able to quell them by turning off login and SSL.
This product is an Open Source disk cloning system similar to Symantec Ghost & Partimage. Provides a few different ways to facilitate a duplication.
This is cool, based on NetBSD and comes with the Ultimate Boot CD (see below). It uses ftp to transfer an image of your entire hard disk, but will also accomodate individual partitions as opposed to partimage which will do partitions only. Therefore it may be more suitable for LVM or BSD (ufs) filesystems which use slices instead of "true" partitions.
To upload an image of the 1st and second SCSI disks (IDE disks would be wd0 and wd1)
uploaddisk ftpuser@ftpserver image-sd0.gz sd0 uploaddisk ftpuser@ftpserver image-sd1.gz sd1
This is how to download a full-disk image and overlay it onto 1st and 2nd SCSI disks
slurpdisk ftpuser@ftpserver image-sd0.gz sd0 slurpdisk ftpuser@ftpserver image-sd1.gz sd1
Like g4u, but runs atop of Linux. Menu-driven, but still a bit clunky. Other than that, works pretty well!
I haven't used this yet, but it looks interesting.
Another rescue disk with many utilities for repair, recovery etc. More of the DOS/Windows types. Have yet to try.
TestDisk can rebuild a partition table and otherwise do some nifty things.
Knoppix contains a plethora of utilities such as dd, e2fsck, resize2fs and more. Highly recommended!
contains the partimage client and server among other useful things. Unfortunately it is getting to be outdated, in particular it doesn't have an up-to-date version of e2fsprogs.
has lots of diagnostic, recovery and disk wiping tools such as g4u and DBAN.
- Linux P2V
- Disk Performance
- physical 2 partimage 2 vir - A blog specific to cloning systems using partimage mediation.
- UDPCast uses multicasting
- Forensics Wiki - Disk Imaging