This is one way you can wipe or overwrite multiple drives simultaneously it requires a little tool called Dcfldd which is available for all distributions. If you are an Ubuntu user you can install Dcfldd from the repositories:
# apt-get install dcfldd
CentOS and Scientific Linux can install Dcfldd from the RepoForge repositories:
# yum install dcfldd
Dcfldd will overwrite drive sdb and sdc with zeroes. You can also increase the block size if you want.
# dcfldd if=/dev/zero of=/dev/sdb of=/dev/sdc bs=4M
If the operation completes successfully you should receive the message No space left on device meaning there is nothing left to overwrite on the drive(s).
5120 blocks (20480Mb) written.dcfldd:: No space left on device
If you don’t beliieve me here is a screenshot displaying the activity taking place on both sdb and sdc.
Dcfldd can become useful for when you have get rid of several drives at once, as you saw the command is quite easy to remember. If you have any questions feel free to leave a comment below and I will do my best to reply as soon as possible. Home page: Dcfldd