What do you mean by
Wt z meant by virtual storage & storage device ?
This is not some IM or Twitter site -- this is a site for mainframe students and beginners. Since a big part of IT is communication, people posting on this forum are expected to use standard English, and it is up to the person writing the post to ensure that clear, precise communication is achieved.
Google is your friend. Googling virtual storage
returns 7,140,000 hits -- some of which on the very first page give the IBM definition. Googling storage device
returns 18,700,000 hits -- and again the very first page has links to the answer you asked for. So the question really is, do we need to teach you how to use Google?