BACKUP OF SAP AND DB

Hi all

If i take backup through DB13 or brtool on disk or Tape then how it will be effective for me if my system crash.

1) i have to install os and sap & restore backup through db12 or brtools ?

2) if i restore backup through db12 or brtools then system will be at same possion as the orignal system was running?. i mean all client & their data ( master data, user data etc) will restored.

or there is a different some thing different

Best Regard,

Imran Khan