Backup and restore using powershell command

Backup

backup-spsite -identity "site-collection-path" -path "backup-location"

where

site-collection-path : http://machinename:port/sites/sitecollectionname

backup-location : D:/backup/site.bak


Restore

restore-spsite -identity "site-collection-path" -path "backup-location" -Force

Note: You can not restore more than one site collection in a web application so you have to create a new database. Below command can be used to overcome this issue.

restore-spsite -identity "site-collection-path" -path "backup-location" -Force -DatabaseName "DBNAME"


To Create a new Database follow below instruction

Goto Central Administration---> Manage Content Databases-->Add New Content Database