How to split the logs of Varnish for Virtual host

Varnish is a great tool that accelerates the performance of your site with a simple configuration and a low usage of resources, compared to the result you’ll get. Just because Varnish is designed and engineered to be fast by default it does not write any log to disk, outrageous you could think – to be honest the logs are available in a memory segment when this memory is filled, Varnish starts from the beginning and overwrites the oldest data in an infinite loop.

So in reality there are logs and they are available for some time, and this solution is much, much faster then logging to a file and it doesn’t require disk space, but how we can get them on file, possibly divided by virtual host as do Apache or Nginx ?