Backup / Restore SharePoint site collection using PowerShell or STSADM commands

• Backup Using PowerShell

Backup-SPSite <URL of the site collection (Ex, http://server_name/sites/site_name)> -Path <full path to the backup file (Ex, C:\Backup\site_name.bak)>

• Backup Using STSADM

stsadm -o backup -url <URL of the site collection (Ex, http://server_name/sites/site_name)> -filename <full path to the backup file (Ex, C:\Backup\site_name.bak)> -overwrite

• Restore Using PowerShell

Restore-SPSite <URL of the site collection (Ex, http://server_name/sites/site_name)> -Path <full path to the backup file (Ex, C:\Backup\site_name.bak)> -Force 

• Restore Using STSADM

stsadm -o restore -url <URL of the site collection (Ex, http://server_name/sites/site_name)> -filename <full path to the backup file (Ex, C:\Backup\site_name.bak)> -overwrite

Note: Using of -overwrite or -Force to overwrite an existing backup file or site collection if it already exists.