shell script to create disk load

friends , need a shell script to create a disk load. can any one pls guide me with how this can be implemented. Pls provide the concept. from there i will try to design my script.

What do you mean by "disk load"? Do you want to fill your disk up, then create a large file using dd. Do you want a high I/O load, then write a file and read it, all within an infinite loop.

The second option. Create a high disk I/O and then write a file and read it.

You could use dd to create a large file with random date:

dd if=/dev/random of=/tmp/largefile bs=1024 count=4000000

That should create you a 4gb file with totally random data from /dev/random.
This usually sufficiently hammers the disk with I/O