If the database is down how to preserve the form data and save it to some other place?Also what can this other place potentially be ?

I have been given a task of saving web-form data to another place when the database is down. Although, by the sound of it I find it a little beyond possible. Is there any way I can achieve this? If not, what is the alternative way by which I can help the user preserve form data even when the database is down. The PHP version I am using is PHP 7