How to completely erase a hard drive making the data impossible to recover?

I have a number of hard drives and external hard drives that I no longer need and would like to sell on ebay. Before I do this I want to make sure the drives are completely erased. I know I can format it but I heard you can still recover data from a drive that has been formatted. Is their a way that I can completely erase a drive making it impossible to recover any data from it.





ThanksHow to completely erase a hard drive making the data impossible to recover?
eraser it works and it's free. you need to use at least 7 passes for secure deletion and 35 if your really worried. it also come with a nuke boot to wipe everything.


http://www.heidi.ie/node/6How to completely erase a hard drive making the data impossible to recover?
Yes, all that needs to be done is to write garbage values all over the old data. When you delete files what really happens is that files' references are removed from the file table. It's still there, but the OS just ignores existence until the hard drive manager writes some data over those same sectors where your old file used to be. So, writing crap values over the old sectors should just remove the data.





Maybe you could use file-shredder to do this, by connecting your target hard-drives to another computer. But, if you really want to prevent someone from getting to your data, just smash the hard drive. Then, there's no way anyone could read your hard disks at that point.
Yes its right formatted hard drive can be recovered... Use shredder to format your drive but i would like to tell you its not that easy to recover so dont worry about this it needs expert skills and some special softwares to recover drives.
google dban. Darik's boot and nuke. Make a cd or floppy, set bios to boot from and follow prompts to securely format all partitions.
Using some shredder (Tuneup Utilities shredder, or SpyBot Search and Destroy's file Shredder), shred all files using 7 or more passes. Then reformat the drive.
Do a full format on the entire drive at lest 7 - 10 times. Then take a hammer to it.
Well I'd never consider buying a second hand hard drive. There is no way of knowing if it actually works or if it is a dead drive
delete all files and uninstall all programs, clear your internet history thats all I got
Dip it into lemon juice =)