Want to know how much time a sccm 2012 backup will take to restore for the working again environment of 30000 clients with all the features enabled. 

There are many variables involved (like disk speed etc). It should be done within a couple of hours max. 

Hi Torsten 

Thanks for the reply can you please help me to know the important variables which are critical for restore is it about the size of backup   etc.

Although Torsten answer is correct, What exactly do you mean by restore?

• Do you mean how long until the site server is up and running?
• Do you mean until clients can run a deployment?
• Do you mean until clients can run a SU?
• Do you mean until clients reports hardware and heartbeat discovery?

Each of those will have different times. It will also depend on if everyone is at one site or multiple sites. How exactly your environment is setup, etc...

Why exactly do you want to know?