MongoDB add backup role

updateUser

> db.getUsers()
[
	{
		"_id" : "admin.ssir-admin",
		"user" : "ssir-admin",
		"db" : "admin",
		"roles" : [
			{
				"role" : "readWrite",
				"db" : "admin"
			},
			{
				"role" : "userAdminAnyDatabase",
				"db" : "admin"
			}
		]
	}
]


db.updateUser( "ssir-admin",
               {
                 roles : [
                   {
                      "role" : "readWrite",
                      "db" : "admin"
                   },
                   {
                      "role" : "userAdminAnyDatabase",
                      "db" : "admin"
                   },
                   {
                      "role" : "backup",
                      "db" : "admin"
                   }
                 ]
               }
             )