I recently purchased Lenovo Ideapad 320 and after using the laptop for few days , i noticed unusual rattling sound coming from the right side of the laptop. when i investigated the cause of the sound i came to know that sound comes from the hard disk . Later on i contacted the nearest service centre of lenovo. after deep troubleshooting by using "Lenovo solution center" we came to a conclusion that condition of hard disk was fine. Moreover they assured me that if any untoward thing happens with the hard disk  they will replace it with a new one, provided the laptop is under warranty.

      I was not completely satisfied with their resolution. I tried to contact the Lenovo online technical support and after waiting for a long in order to get a live conversation with any technical agent, i finally established a contact and the agent on other side gave me the resolution that it is a usual sound with slim hard disks, nothing to worry about.