Using a linux livecd for Data recovery

This one makes into the hardware AND software categories. I don’t remember how many times I’ve replaced a failing hard drive. Usually the biggest headache and anxiety is if you’ll be able to get any data off of the old drive. Sometimes if luck holds and the system can read both the old and the new drives, you can easily. You can just copy data from the old drive to the new one. But sometimes you’re not as lucky, the drive starts to have reading errors and things go from bad to worse.

Now, one reason I enjoy using linux is there are so many tools available for those “impossible” situations. One data recovery cd I’ve used is something called ghost4unix (g4u for short) and it does a nice job of “cloning” the contents of one drive onto another. It’s built on one of the BSD Unices, so it’s a cousin of sorts to the linux boot cds I’ve mentioned lately. It basically copies the disks contents exactly and is unaware of file system information, meaning that if the disc with g4u boots and recognizes your hardware, you’re in good shape. Some other interesting features include the ability to image a drive directly to a file on a remote server. In one instance, I’ve used this to make a backup of critical machine. I setup an ftp server, booted the machine with this disc, it automatically copied the image to a file on the ftp server and from there I copied the image to cd for safekeeping. It’s possible then to do the reverse and to “slurp” the image from the server back to the machine to re-image the drive. It’s certainly a nice tool.

Unfortunately one of the drawbacks I’ve found is when a drive is failing. The method of copying that g4u uses has a tendancy to

bail out if there are read errors on the hard drive. Enter the tool called dd_rescue. dd_rescue is a neat variation of dd (which is a direct copying program under *nix systems). dd_rescue does not give up when it finds read errors with a disc, instead it skips far ahead and works backwards towards the area that failed. It tries then to get every bit of readable data off of a drive. It is probably the cheapest data recovery solution you could find.

You don’t need to use it on it’s own though, there is another tool called ghost4linux (g4l) that includes some of the features of g4u, plus the dd_rescue tool for troublesome drives and a few other features in a graphical interface. Now, g4l has had it’s share of controversy. G4u authors accused an earlier version of being a line for line copy of their code without credit. This is a violation of the BSD license. G4l authors argue that it’s been completely rewritten since then and there is a new programmer at the lead as far as I understand. Additionally, g4u authors have not reviewed more recent versions of the g4l scripts.

I’ve used ghost4linux (g4l) several times on drives that I thought were lost. In both cases there were bad areas that were unreadable and caused other tools to fail, but the dd_rescue component of g4l managed to clone the entire drive. In neither case was a reinstall of windows required, although when you do “skip” or lose any data there is that possibility. Mostly, they were just happy to see their data again. A reinstall wouldn’t have been as painful as having to replace the irreplacable data.

So, if you’re in need of a program for data recovery, you might consider trying out ghost4linux or ghost4unix, both come as bootable cd’s. Ghost4unix comes as a floppy image as well.

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