Hi All
Thanks for the reply. but this was not what I wanted
Sorry that I was not very specific in my question.
The fact is that format, newfs, and rm will not erase all the data blocks. anybody who is interested in the data can still retrieve it using some tools.
what I wanted to do was to rewrite all the datablocks with some random numbers or zeros.
finally I found a way out using the following command
dd if=/dev/zero of=/dev/rdsk/c0t1d0
this rewrites all the blocks with zeros..I tested it with a third party tool to view sectors(Expert Eraser-a dos program)after connecting the same disk to a PC.
Thanks®ards
Mohan